close up of sandwich on a white board

Blackened Cod Sandwich

  • Author: Hey Emily Ann
  • Prep Time: 5 minutes
  • Cook Time: 10 minutes
  • Total Time: 15 minutes
  • Yield: 2 sandwiches 1x


A super delicious and easy fish sandwich.



  • 2 (5 oz) Cod fillets
  • 2 brioche buns
  • 1 tbsp corn starch
  • 1 tsp garlic powder
  • 1 tsp onion powder
  • 1/2 tsp cayenne pepper
  • 1/2 tsp chili powder
  • 1/2 tsp salt
  • 1/2 tsp black pepper
  • 1 yellow onion
  • 1 avocado
  • 1 globe tomato
  • 2 tbsp mayonnaise
  • 1 tsp hot sauce
  • 1/2 tsp chili powder
  • canola oil


To prepare the caramelized onions: slice onion into thin slices, as thin as you are able. Heat up 1 tsp of olive or canola oil in a medium skillet and add onions. Reduce heat to low and continue cooking onions, stirring occasionally. After ~30 minutes of cooking the onions should be a caramel color and ready to go!

To Prepare the Cod fillets: pat cod dry with a paper towel. In a small bowl, combine the corn starch garlic powder, onion powder, cayenne and chili powder, and and pepper and mix together. Cover the top and bottom of fillets with seasoning.

Heat up a large skillet with canola oil. Place cod fillets on skillet and flip after 3 minutes. Cook for 3 minutes on the other side, and continue cooking until the cod reaches an internal temp of 145.

To Prepare the spicy mayo: in a small bowl combine the mayo, hot sauce and 1/2 tsp chili powder. Stir together.

To prepare the sandwiches: toast the brioche buns in a toaster or oven until lightly brown. Smear bottom bun with spicy mayo, top with cod, caramelized onions, a slice of tomato, and a smear of avocado on the top bun. Serve immediately.


This recipe can easily be doubled, or tripled! Just multiply every ingredient by either 2 or 3, whichever amount you are going for!

  • Category: Dinner
  • Method: Pan Fry
  • Cuisine: American

Keywords: cod, caramelized onion, sandwich, dinner