If you want a little taste of vacation,  try out our Blackened Fish Sandwich Recipe. This easy fish sandwich is pan-seared until crusty and blackened on the top and flaky inside, nestled into a brioche bun, and topped with a lime and cumin Brussels sprout slaw. 

If you want a little taste of vacation,  try out our Blackened Fish Sandwich Recipe. This easy fish sandwich is pan-seared until crusty and blackened on the top and flaky inside, nestled into a brioche bun, and topped with a lime and cumin Brussels sprout slaw. 

Blackened Fish Sandwich Recipe with Brussels Sprout Slaw

Gosh, there really isn’t anything better than a spicy, pan-seared piece of flaky, moist, perfectly-tender fish tucked into a buttery brioche bun and covered in zippy Brussels sprout slaw.

Unless that buttery brioche bun is slathered with mayo. (This Fish Reuben is pretty close up there as well.)

The choice of mayo or no may is up to you, you can follow my lead on the rest. 

This easy version of a restaurant-quality blackened fish sandwich recipe (oh, and a healthy fish sandwich recipe) may be deceiving at first glance, because well, it looks like it came from a restaurant, but rest assured, you can whip up this beauty in your own home in no time. 

While the lime and cumin-laced dressing is working its magic on the shredded Brussels sprouts, you cook your fish – we’re using halibut – in a little bit of butter or olive oil, toast the buns, and then sandwich everything together. From start to finish, you’re looking at a mere 30 minutes of prep and cook time, and that is reason enough to whip this up on a toasty summer night. 

Blackened Halibut Sandwich with Brussels sprout Slaw

Ingredients in our Blackened Fish Sandwich Recipe

The slaw

Lime juice. To compliment the blackened fish, it only made sense to use a little bit of lime just as the acid in our Brussels sprout slaw. A little bit of acid is important in a slaw, especially a Brussels sprout slaw to help break down some of the tougher pieces. I use a good amount, about two tablespoons, which equals about two small limes or one large one. 

Cumin. I love the smokiness of cumin, and find that it works really well in a slaw. A little goes a long way here, so while I usually use a generous amount, in this case, I hold back a little bit. 

Mayo. No proper slaw is complete without mayo, but we use a scant amount, and always use a light version to keep calories down. 

Honey. Any time I make a dressing, I almost always add a little bit of honey. It balances out the acid from the lime juice and adds just a hint of sweetness. 

Salt and Pepper. A given. 

Red bell pepper. To add a little bit of color and extra crunch, we add in about half cup of diced red bell pepper. 

Cilantro.  We’ve got lime, cumin, and spiciness, so there must be cilantro. And if you’re anything like me, there’s  lots of it. Feel free to add as much or as little as you would like. 

Brussels sprout slaw with lime, cumin, and cilantro

The sandwich

Fish. To make a great fish sandwich, you want a great piece of fish. We used halibut, which is a slightly firm, flaky white fish, but mahi mahi or grouper would be good substitutes. You also want to make sure to buy center-cut filets since they are uniform in size throughout the piece of fish. They also tend to be thicker which works better for a sandwich. 

Blackening spices. Normally I throw together my own blackening spices which include paprika, oregano, garlic powder, onion powder, black pepper, cayenne, and salt, but I actually had a jar of blackening seasoning on hand, so that’s what I used. 

Olive oil or butter. For the fish to truly be blackened, it needs to be seared in butter, but I often swap out the butter for olive oil so it’s a little more heart-healthy. 

Bun. The bun is a big deal on a good fish sandwich, let alone any sandwich. You don’t want it to overpower the delicate fish, but you also want it to be sturdy enough to hold everything together. Our bun of choice is a brioche bun since it’s a little bit more dense than a classic hamburger bun, but still light and super flavorful. 

Mayo. I am a sucker for mayo-slathered buns, and this sandwich is no exception. It may seem like an excessive addition, but it’s pretty darn good. Feel free to leave it off. 

Avocado. Because avocado is delicious on everything. 🙂

Nuts. Even though the red pepper and the Brussels sprouts have a nice crunch to them, I like to add even more texture with chopped cashews. They’re sweet, buttery, and gosh, they’re good. 

Sear halibut in a cast-iron skillet

Let’s make a blackened fish sandwich recipe! 

Make the slaw. We make the slaw first, so it has time to soak up all the dressing. Whisk the lime juice, mayo, cumin, salt, and honey together in a medium bowl.

Add in the Brussels sprouts, chopped red bell peppers, and cilantro. Stir to combine. Let it set while you cook the fish. 

Sear the fish. Sprinkle the halibut filets with blackening spice on both sides. Heat a large cast-iron skillet to a medium-high heat. Add enough oil or butter to lightly coat the bottom of the pan. Once the oil is hot and shimmers, turn the pan so it’s evenly coated.

Gently nestle the fish into he hot pan, cook 3-4 minutes, flip and cook another 3-4 minutes until cooked all the way through. You will know it’s done when it flakes easily and is white throughout the fish. 

Assemble! Spread a little bit of mayo on the bottom of the bun. Spoon a little bit of the slaw on the bun. Top with a piece of fish. Layer avocado on top. Sprinkle with salt and pepper. Pile more slaw on top. Cover with top bun.  

How to make your own blackening seasoning

If you have the spices on hand, you may as well make your seasoning. Use the recipe from our Blackened Tilapia with Watermelon Salsa, you’ll need: 

  • 1 teaspoon paprika
  • 1 teaspoon garlic powder
  • 1 teaspoon onion powder
  • 1 teaspoon oregano
  • 1/4 teaspoon cayenne
  • 3/4 teaspoon salt

Substitutions and Tips and Tricks for Recipes

  • Swap out halibut for mahi mahi, swordfish, or grouper
  • For a little kick, add a little bit of asian chili sauce to the mayo before slathering it on the bottoms of the buns
  • Use your favorite bun, this would also be great on an egg bun or pretzel bun
  • Portion the fish into smaller pieces and serve on slider buns
  • If you’re worried about cooking
  • Refrain from flipping the fish before it’s ready, it will release easily from the pan when it’s ready to turn. 

If you love a good sandwich, don’t miss these other favorites! 

Halibut sandwich with Brussels sprout slaw

Blackened Fish Sandwich Recipe

If you want a little taste of vacation,  try out our Blackened Fish Sandwich Recipe. This easy fish sandwich is pan-seared until crusty and blackened on the top and flaky inside, nestled into a brioche bun, and topped with a lime and cumin Brussels sprout slaw. 

Course Main Course
Cuisine American
Keyword blackened fish sandwich, fish sandwich, halibut fish sandwich
Prep Time 10 minutes
Cook Time 15 minutes
Total Time 25 minutes
Servings 4 sandwiches
Calories 628 kcal
Author Nicole


  • 2 tbsp lime juice
  • 1 tsp honey
  • 1/4 tsp ground cumin
  • 1/4 tsp kosher salt
  • 1/4 cup light mayo, divided
  • 2 cups shredded brussels sprouts
  • 1/2 cup diced red bell pepper
  • 2 tbsp chopped cilantro
  • 2 tsp blackening season (See notes)
  • 1 tbsp olive oil or butter
  • 1 lb center-cut halibut fliets (4- 4-ounce portions)
  • 4 brioche buns
  • 1/2 medium avocado, sliced thin
  • 2 tbsp chopped cashews


  1. Add the lime juice, honey, cumin, salt, and 2 tablespoons mayo in a medium bowl. Whisk to combine. Season with salt and pepper. Add the shredded brussels sprouts, diced red pepper, and cilantro. Stir to combine. Set aside.

  2. Sprinkle the halibut filets generously with salt and pepper. Sprinkle evenly with the blackening season.

  3. Heat a large cast-iron skillet to a medium-high heat. Once the pan is hot, add olive oil or butter. Swirl the pan to coat it. Once the oil is hot, gently nestle the fish in the pan. Cook for 3-4 minutes until it easily releases from the pan. Flip and cook another 3-4 minutes until cooked through. It should flake easily and be nice and white throughout. Remove from the pan.

  4. Before assembling, give the slaw a stir and see if it needs any more salt and pepper. Spread the bottom bun with a little bit of mayo. Top with a littl bit of slaw and a piece of halibut. Layer a few pieces of avocado on top. Season with salt and pepper. Top with more slaw and the rest of the bun. Enjoy!

Nutrition Facts
Blackened Fish Sandwich Recipe
Amount Per Serving (1 sandwich)
Calories 628 Calories from Fat 297
% Daily Value*
Fat 33g51%
Saturated Fat 13g81%
Cholesterol 201mg67%
Sodium 725mg32%
Potassium 859mg25%
Carbohydrates 51g17%
Fiber 4g17%
Sugar 4g4%
Protein 34g68%
Vitamin A 1747IU35%
Vitamin C 66mg80%
Calcium 77mg8%
Iron 2mg11%
* Percent Daily Values are based on a 2000 calorie diet.
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