Meatless Monday Challenge

20-Minute Cajun Mahi-Mahi Sandwich

on June 21, 2024
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This Mahi-mahi sandwich uses simple ingredients and makes the most of them for a flavorful, fulfilling meal with the perfect amount of salt and spice.
Sub-style sandwich with Cajun pan-fried mahi mahi, lettuce, tomato, and tartar sauce.

Craving a flawless fish sandwich? This Mahi-Mahi Sandwich hits all the right notes: seasoned to perfection, impeccably cooked, and quick and easy to make.

The Cajun seasoning brings just the right amount of salt and spice, the cooking method gives the pan-fried mahi-mahi a crisp exterior, and it all comes together beautifully with toppings and sauce between bread.

Cajun Mahi-mahi sandwich on a hoagie roll with lettuce and tomato.

Mahi-Mahi Sandwich Ingredients

Here’s everything you need:

  • Mahi-mahi. This sandwich recipe will also work with other fish!
  • Cajun seasoning.
  • Olive oil.
  • Hoagie rolls.
  • Lettuce, tomato, and tartar sauce. Or whichever toppings and sauces you prefer in your fish sandwiches.
overhead view of all ingredients for mahi-mahi sandwich - tartar sauce, hoagie rolls, tomato, olive oil, Cajun seasoning, mahi-mahi, lettuce

Sustainable Seafood

Mahi-Mahi is generally considered a sustainable fish to eat as it is fast-growing and has a short life cycle. They are generally caught from marine fisheries (not fish farms) utilizing longlines which means little to no bycatch!

Green tip: The most sustainable way to eat Mahi-Mahi is to look for U.S. Atlantic Mahi-Mahi.

How to Make a Fish Sandwich with Mahi-Mahi

How to Prep Mahi-Mahi for a Fish Sandwich

I used pre-portioned mahi-mahi that was already skinless. If you need to remove the skin and portion your mahi-mahi out, do that first. Then, use paper towel to blot the fish, reducing any excess moisture.

This will not only give you the best texture on your fish, but will also allow the seasoning to more readily stick to it. Add a generous amount of seasoning to both sides of the fish.

The amount of seasoning you use will depend on the particular brand of seasoning you use. Some brands, like Slap Ya Mama have a much higher salt and spice content than others like McCormick. The measurements I used for this recipe are with McCormick.

Blotting raw Mahi-mahi with paper towel to reduce the amount of moisture in the fillets.
Blot the mahi-mahi dry with a paper towel.
Seasoning two fillets of fish with Cajun seasoning on both sides.
Season the fish with Cajun seasoning.

How to Perfectly Pan-Dry Mahi-Mahi

The key is getting the oil hot first. Add the oil to the pan over medium-high heat and let it heat up for 3-5 minutes. When you drop the fish in, it should immediately sizzle.

Pan-fry for about 3-5 minutes on each side, covered (to both trap the heat and to avoid splattering oil) until the internal temperature of the fish reaches 145°F.

If you want cheese on your sandwich, add it once you flip the fish.

Lowering seasoned fish into hot oil in a pan.
Get the oil hot and drop the fish in.
Mah-mahi pan frying in olive oil to cook for a sandwich.
Pan-fry for 3-5 minutes on each side covered.

How to Assemble a Fish Sandwich

Start with a hoagie roll (or any bread of choice). Mine were super fresh, so I decided to leave it as is, but you can choose to toast it if you want.

Then, add the tartar sauce, or any sauce of choice. When I’m not using tartar sauce, I love using the sauce from this Salmon Tacos with Greek Yogurt Sauce recipe.

Next, add your greens of choice. This will act as a buffer between the juicy tomatoes and fish and the bread, so that it doesn’t get too soggy.

Add your tomato slices next and/or any other toppings of choice. Finish with the pan-fried mahi-mahi and fold it over to complete your sandwich.

Building a Mahi-mahi sandwich step 1 - adding tartar sauce.
Start by adding the sauce to the bread.
Building a Mahi-mahi sandwich step 2 - adding lettuce.
Next, add your greens.
Building a Mahi-mahi sandwich step 3 - adding tomato.
Then, add the sliced tomato.
Building a Mahi-mahi sandwich step 4 - adding fish.
Finally, add your cooked fish.

Serving Your Sandwich with Mahi-Mahi

This fish sandwich is nice and hearty, and makes a full meal on its own, but if you’re looking for some sides, I got you! Pictured I just served with freezer air fryer sweet potato fries, but here are some of my other favorites:

Fish sandwich with Cajun Mahi-mahi served with a bucket of sweet potato fries.

How to Properly Store and Reheat Mahi-Mahi Sandwich

If possible, it’s best to store the blackened mahi-mahi separately from the bread and toppings, and then re-build the sandwich after reheating the fish.

Cooked Mahi-Mahi will stay fresh stored in an airtight container in the refrigerator for another 3-4 days after preparation.

The best way to reheat it is to cover it and place it in your preheated oven at 275 °F, for about 15 minutes or until the internal temperature reaches 145°F.

Green tip: Did you know that of the billions of pounds of food wasted annually, it is estimated that 50% of it happens in our homes. It’s always best to avoid food waste as much as you can! That means storing your leftovers properly.

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Why this is the best Mahi-mahi Sandwich Recipe

  • It’s simple. Just a 3-ingredient Cajun-spiced fish, bread, and toppings and you’ve got all the flavors and textures you need.
  • It’s so quick. This fish lunch or dinner comes together in just 20 minutes (or even less once you get the hang of it).

If you’re loving this Mahi-Mahi sandwich and want more delicious, pan-fried fish recipes, check out this Lemon Butter Halibut and Cajun Salmon and Grits.

Sub-style sandwich with Cajun pan-fried mahi mahi, lettuce, tomato, and tartar sauce.

20-Minute Cajun Mahi-Mahi Sandwich

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Marley Goldin
This Mahi-mahi sandwich uses simple ingredients and makes the most of them for a flavorful, fulfilling meal with the perfect amount of salt and spice.
Prep Time 10 minutes
Cook Time 10 minutes
Total Time 20 minutes
Servings 2 sandwiches


  • 12 ounces mahi-mahi
  • 1 tablespoon Cajun seasoning
  • 1 tablespoon olive oil
  • 2 hoagie rolls
  • 1 tablespoon tartar sauce
  • greens of choice (I used lettuce)
  • sliced tomato


  • Pat dry your Mahi-Mahi with paper towels (use these bamboo paper towels for a more sustainable option!) and set aside. Discard the paper towels and wash your hands.
  • Season the Mahi-Mahi on both sides with Cajun seasoning (see notes).
  • Over medium-high heat, get the oil hot in the pan for 3-5 minutes. Then, carefully lower the fish into the hot oil and cover.
  • Pan-fry the fish for 3-5 minutes on each side. The mahi-mahi should easily peel off the pan when it's ready to flip. If it's stuck, don't force it, just give it extra time until it naturally releases from the pan.
  • Assemble your sandwich by adding the sauce, then the greens, then the tomato and then the fish between your bread. Enjoy!

Pro Tips

  • Please note: the measurements in this recipe are for using a standard Cajun seasoning blend like McCormick. However, if you’re using a seasoning blend that’s heavier on the salt and spice, like Slap Ya Mama Cajun Seasoning for example, you will likely want to use less seasoning.
  • If you want to add cheese, add it to the pan with the fish cooking after you flip it. 
  • The bread, sauces, and toppings can be mixed up to make this sandwich your own!
Course Dinner, Lunch
Cuisine American
Keyword 30 Minutes or Less, Blackened Mahi-Mahi, Fish Sandwich, Pescatarian, Sandwich
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