Sheet Pan Blackened Mahi-Mahi Sandwich with High-Protein Remoulade

Sheet Pan Blackened Mahi-Mahi Sandwich with High-Protein Cajun Remoulade and Crispy Cabbage Slaw

When I first moved to New York City from Morocco, I was blown away by the bold, smoky flavors of Cajun street food. Growing up in Marrakech, my mother would blacken fish in a scorching cast-iron pan with a blend of spices that danced between sweet paprika and fiery cayenne. That memory stuck with me. So when I trained in Paris and later settled in NYC, I knew I had to create a blackened mahi mahi sandwich recipe that honored that heat but kept things light, fast, and completely sheet-pan friendly. This recipe — with its homemade High-Protein Cajun Remoulade — is exactly that: a 25-minute dinner that tastes like you spent all day in a Southern kitchen.

Let me walk you through the magic. The mahi-mahi fillets get a generous rub of my signature blackening seasoning — smoked paprika, cayenne, garlic powder, onion powder, oregano, and thyme — then roast on a single sheet pan until the edges are charred and the interior flakes like butter. Meanwhile, the cabbage slaw, tossed in apple cider vinegar and a pinch of sugar, stays cool and crunchy, cutting through the remoulade’s creamy richness. The remoulade itself is a high-protein twist on the classic: thick Greek yogurt replaces mayo, giving you a tangy, protein-packed spread that clings to every bite without weighing you down.

I’ve tested this sheet pan fish sandwich more times than I can count — for busy weeknights, for weekend meal prep, even for friends who swore they didn’t like fish. The winning strategy? Don’t skip the butter-toasted brioche buns. They add a soft, buttery contrast that makes every ingredient shine. And here’s a pro tip I learned from my Paris days: let the cabbage slaw sit for at least five minutes while the fish bakes — that brief marination is what gives it that perfect pickle-crunch. One common mistake? Overcrowding the sheet pan. Give those fillets room to breathe, and you’ll get the signature blackened crust every time.

Why This Blackened Mahi-Mahi Sandwich Recipe Is the Best

The Flavor Secret — This isn’t just another blackened fish sandwich. My High-Protein Cajun Remoulade is the game-changer. By using 0% Greek yogurt instead of mayo, I’ve created a sauce that’s both rich and light, with a protein boost that complements the mahi-mahi perfectly. The combination of Dijon mustard, Cajun seasoning, hot sauce, and capers brings a tangy, briny kick that echoes the best New Orleans po’boys. My mother’s Moroccan spice blend — heavy on smoked paprika — gives the fish a deep, earthy warmth that you won’t find in store-bought seasoning. Every bite is a fusion of my heritage and my training: North African heat meets French sauce-making meets NYC’s love for bold, fast flavors.

Perfected Texture — Baking at 425°F on a sheet pan delivers even, gentle heat that puffs up the fillets without drying them out. The key? Brushing them with olive oil before the seasoning so the spices toast rather than burn. The slaw stays intentionally light — no heavy dressing — just vinegar, oil, and a whisper of sugar to brighten the cabbage. And the remoulade’s thickness means it clings to the fish without making the bun soggy. I learned that trick in Paris: always balance moisture levels between components so every layer stays distinct.

Foolproof & Fast — If you can measure spices and preheat an oven, you can make this sheet pan fish sandwich. No deep-frying, no splattering oil, no complicated techniques. The entire hands-on time is about 15 minutes. Even beginners will nail it on the first try because the visual cues are so clear — the fish should flake easily when gently pressed, and the cabbage should be crisp-tender. I’ve made this for friends who never cook fish, and they’ve all walked away asking for the recipe. It’s that reliable.

Blackened Mahi-Mahi Sandwich Recipe Ingredients

I pick up my mahi-mahi from the fish counter at the Union Square Greenmarket — sustainably caught and always fresh. The cabbage I get from a local farm in Jersey; it’s incredibly crisp this time of year. And the Greek yogurt? I have a little obsession with Fage 0% — it’s thick, creamy, and nowhere near as watery as other brands. Every ingredient here is chosen to build the perfect sandwich: bold, balanced, and weeknight-easy.

Ingredients List

• For the Sheet Pan:
• 4 mahi-mahi fillets (4 oz each)
• 1 tbsp olive oil
• 1 tbsp blackening seasoning (smoked paprika, cayenne, garlic powder, onion powder, oregano, thyme)
• salt
• For the Crispy Cabbage Slaw:
• 1 1/2 cups shredded green cabbage
• 1/4 cup shredded purple cabbage
• 1 tbsp apple cider vinegar
• 1 tsp olive oil
• pinch of sugar
• pinch of salt
• For the High-Protein Cajun Remoulade:
• 1/2 cup Greek yogurt (0% fat)
• 1 tbsp Dijon mustard
• 1 tsp Cajun seasoning
• 1 tsp hot sauce (like Tabasco or Crystal)
• juice of 1/2 lemon
• 1 tsp capers (chopped)
• 1 garlic clove (minced)
• pinch of salt
• For the Assembly:
• 4 brioche buns (toasted)
• butter for toasting
• lemon wedges for serving

Ingredient Spotlight

Mahi-Mahi Fillets: This firm, lean fish is perfect for blackening because it holds its shape and doesn’t fall apart. Look for fillets that are 1-inch thick for even cooking. Frozen works fine — just thaw overnight in the fridge and pat dry. Substitution: cod or halibut (same flaky texture, slight different flavor).

Blackening Seasoning: I make my own blend to control the heat and salt. Smoked paprika is non-negotiable — it gives that deep, campfire-char flavor. Substitution: store-bought blackening seasoning (like Paul Prudhomme’s) works, but watch sodium levels.

Greek Yogurt (0% Fat): This is the secret to the high-protein remoulade. Full-fat Greek yogurt also works for a creamier sauce, but 0% keeps it lighter. Substitution: plain skyr (even more protein) or avocado (for a dairy-free option, though texture changes).

Green and Purple Cabbage: The combo adds both crunch and color. Green cabbage is milder; purple adds a peppery bite and gorgeous hue. Substitution: coleslaw mix from the store (skip the dressing packets) or shaved Brussels sprouts for a nutty twist.

Original Ingredient	Best Substitution	Flavor / Texture Impact
Mahi-mahi	Cod or halibut	Similar flaky texture; cod is milder
Blackening seasoning	Store-bought Cajun blackening spice	Saltier; reduce added salt
Greek yogurt (0%)	Full-fat Greek yogurt or skyr	Richer, a bit more tang; protein stays high
Cabbage (green + purple)	Shredded Brussels sprouts or coleslaw mix	Brussels add nutty flavor; coleslaw mix is milder
Brioche buns	Brioche, potato buns, or lettuce wraps (low-carb)	Brioche is soft and buttery; lettuce keeps it light

How to Make Blackened Mahi-Mahi Sandwich — Step-by-Step

Trust me, this is one of the easiest recipes in my rotation. With five simple steps and one sheet pan, you’ll have a restaurant-quality sandwich on the table in under 30 minutes.

Step 1: Season and Bake the Fish

Preheat your oven to 425°F (220°C). Line a sheet pan with parchment paper or foil for easy cleanup. Pat the mahi-mahi fillets dry with paper towels, then brush each fillet with olive oil. In a small bowl, combine the blackening seasoning with a pinch of salt. Rub the seasoning generously over both sides of each fillet. Place them on the prepared sheet pan, leaving at least an inch of space between each one.

💡 Sara’s Pro Tip: Don’t skimp on the seasoning! The blackening crust is what gives this sandwich its signature smoky, charred flavor. Press the seasoning into the fish gently so it adheres.

Step 2: Bake to Perfection

Bake the mahi-mahi for 10 minutes, or until the edges are slightly charred and the fish flakes easily when tested with a fork. Every oven is slightly different, so start checking at 9 minutes. The internal temperature should reach 145°F. No need to flip — the sheet pan does all the work.

⚠️ Common Mistake to Avoid: Overcrowding the pan. If you place the fillets too close together, they’ll steam instead of blacken. Use a larger sheet pan or bake in two batches if needed.

Step 3: Prepare the Slaw

While the fish bakes, combine the shredded green cabbage and purple cabbage in a medium bowl. Drizzle with apple cider vinegar, olive oil, sugar, and a pinch of salt. Toss well and set aside to marinate. This quick pickling process softens the cabbage slightly while keeping it crunchy — the perfect contrast to the rich remoulade.

💡 Sara’s Pro Tip: For extra crunch, add a handful of shredded carrots or radishes. The slaw will keep its texture for up to 2 hours in the fridge if you’re prepping ahead.

Step 4: Make the Remoulade

In a small bowl, whisk together the Greek yogurt, Dijon mustard, Cajun seasoning, hot sauce, lemon juice, chopped capers, minced garlic, and a pinch of salt. Taste and adjust the heat or tang. The remoulade should be thick enough to spread — if it seems too runny, add a little more yogurt.

⚠️ Common Mistake to Avoid: Don’t skip the capers! They may seem optional, but their briny bursts lift the whole sandwich. If you don’t have capers, a tiny pinch of chopped pickles works too.

Step 5: Toast and Assemble

Split the brioche buns and butter the cut sides. Heat a skillet over medium heat and toast the buns, buttered side down, until golden and slightly crisp — about 2 minutes. Now build your sandwich: spread a generous layer of remoulade on both halves of each bun. Place a blackened mahi fillet on the bottom half, then pile the cabbage slaw on top. Close with the top bun and serve immediately with lemon wedges on the side.

💡 Sara’s Pro Tip: For the neatest eating experience, wrap each sandwich in parchment paper before cutting in half — the remoulade stays in place and the slaw doesn’t tumble out.

Step	Action	Duration	Key Visual Cue
1	Season fish and place on sheet pan	5 min	Seasoning clings evenly
2	Bake fillets	10 min	Edges darken, fish flakes
3	Toss slaw	2 min	Cabbage slightly softened, shiny
4	Whisk remoulade	3 min	Thick, creamy, no lumps
5	Toast buns and assemble	5 min	Buns golden, sandwich stacked neatly

Serving & Presentation

This is a sandwich that deserves a little fanfare. Serve each one immediately after assembly — the contrast between warm, flaky fish and cool, crunchy slaw is at its peak right then. I like to arrange the sandwiches on a wooden board with lemon wedges tucked between them, and maybe a handful of kettle chips or a side of sweet potato fries. For a lighter meal, pair it with a simple green salad dressed in lemon vinaigrette.

When I was in cooking school in Paris, we learned that presentation is about creating a story on the plate. For this sandwich, I love to add a sprinkle of fresh parsley or chives on top of the slaw — it echoes the herbs in the blackening seasoning and adds a pop of green. A side of pickled okra or jalapeños (a nod to my NYC Southern roots) cuts through the richness beautifully.

If you’re hosting a casual dinner, double the recipe and set up a sandwich bar — let guests choose their own remoulade heat level or add sliced avocado. It’s always a hit, especially with a cold IPA or a zesty white wine like Sauvignon Blanc. From my kitchen in the West Village to yours, this is the kind of meal that makes everyone feel like they’re at a weekend cookout — even on a Tuesday.

Pairing Type	Suggestions	Why It Works
Side Dish	Sweet potato fries, kettle chips, or a classic coleslaw	Adds crunch and sweetness; slaw keeps the cabbage theme
Sauce / Dip	Extra remoulade, sriracha aioli, or mango salsa	Remoulade doubles as dip; salsa adds freshness
Beverage	Craft IPA, Sauvignon Blanc, or sparkling limeade	IPA cuts spice; white wine matches the fish; limeade cleanses palate
Garnish	Fresh parsley or chives, lemon wedges, pickled jalapeños	Adds color, brightness, and a tangy kick

Make-Ahead, Storage & Reheating

I’m all about meal prepping for the week — especially when I’m shooting content or running between the market and my NYC apartment. This recipe works beautifully when you prepare components in advance. The remoulade and slaw can be made a day ahead; just keep them chilled. The fish is best fresh, but leftovers store well too.

Method	Container	Duration	Reheating Tip
Refrigerator	Airtight container (store fish & slaw separately)	Up to 3 days	Reheat fish in a 300°F oven for 5 min; serve slaw cold
Freezer	Freezer-safe bag (fish only); slaw does not freeze well	Up to 2 months	Thaw in fridge overnight; reheat in oven at 350°F for 8 min
Make-Ahead	Remoulade & slaw in separate containers	Remoulade up to 4 days, slaw up to 2 days	Assemble just before serving; toast buns fresh

If you’re planning to serve this for a party, I recommend making the remoulade and slaw a day ahead. On the day of, simply bake the fish and toast the buns. Reheating leftover fish in the microwave will make it rubbery, so always use the oven or a toaster oven to preserve that blackened crust. The slaw will lose its crunch if stored too long, so only make as much as you’ll eat within 48 hours.

Variations & Easy Swaps

This recipe is incredibly flexible. Whether you’re catering to dietary needs or just want to shake things up, here are three variations I’ve perfected in my own kitchen.

Variation	Key Change	Best For	Difficulty Impact
Mediterranean Mahi	Swap Cajun remoulade for tzatziki; add feta and olives	Lighter, Mediterranean flavors	Easy
Gluten-Free + Dairy-Free	Use gluten-free buns; replace yogurt with vegan mayo	Allergies & sensitivities	Easy
Mango-Habanero Twist	Add diced mango and habanero to slaw; extra hot sauce	Spice lovers, summer picnics	Medium

Mediterranean Mahi

This variation is a nod to my Moroccan roots. Instead of the Cajun remoulade, use a thick Greek tzatziki (yogurt, cucumber, garlic, dill). Top the fish with crumbled feta, kalamata olives, and a sprinkle of za’atar. The bright, herby flavors transport you straight to a seaside taverna. The cabbage slaw stays the same, but you could swap in shredded romaine for a softer texture.

Gluten-Free + Dairy-Free

I’ve served this to friends with celiac and dairy sensitivities, and they rave about it. Use certified gluten-free buns (I like O’Dough’s or Schar). For the remoulade, replace Greek yogurt with a high-quality vegan mayo — just add a little lemon juice and Dijon to mimic the tang. The blackening seasoning is naturally gluten-free, but double-check your blend. The slaw is already dairy-free, so you’re good there.

Mango-Habanero Twist

When summer hits and mangoes are at their peak at the Union Square Greenmarket, I go for this version. Dice half a ripe mango and a seeded habanero (or jalapeño for less heat) and fold them into the cabbage slaw. Add an extra splash of lime juice. The sweetness of the mango balances the heat of the habanero, and the remoulade gets a few extra dashes of hot sauce. It’s a show-stopping sandwich that’s equally delicious on a picnic or a backyard BBQ.