Blackened Grouper Sandwiches with Key Lime Tartar and Pickled Red Onion

Steps

1. Step 1

   Put the sliced red onion in a heatproof jar or bowl. In a small saucepan, bring the vinegar, water, sugar and salt to a simmer, stirring until the sugar dissolves, then pour it over the onion. Press the onion down so it is submerged and let it sit while you make everything else, at least 20 minutes.

   20 min, hands-off

   • 1 small red onion
   • 1/2 cup white vinegar
   • 1/2 cup water
   • 1 tbsp sugar
   • 1 1/2 tsp kosher salt
2. Step 2

   Stir together the mayonnaise, chopped pickles, capers, key lime juice and zest, dill, and Dijon in a small bowl. Season with salt and pepper, then refrigerate until serving.

   5 min

   • 3/4 cup mayonnaise
   • 3 tbsp dill pickles
   • 1 tbsp capers
   • 2 tbsp key lime juice
   • 1 tsp key lime zest
   • 1 tbsp fresh dill or parsley
   • 1 tsp Dijon mustard
   • salt and black pepper
3. Step 3

   In a shallow dish, mix the paprika, garlic powder, onion powder, thyme, oregano, salt, black pepper and cayenne together to make the blackening rub.

   3 min

   • 1 tbsp sweet paprika
   • 1 1/2 tsp garlic powder
   • 1 tsp onion powder
   • 1 tsp dried thyme
   • 1 tsp dried oregano
   • 1 tsp kosher salt
   • 3/4 tsp black pepper
   • 1/2 tsp cayenne pepper
4. Step 4

   Pat the grouper dry again. Brush both sides of each fillet with about 2 tbsp of the melted butter, then press all sides into the spice mix so they are generously coated. Set on a plate.

   5 min

   • 4 skinless grouper fillets (about 6 oz each, 1 inch thick)
   • 2 tbsp unsalted butter
5. Step 5

   Brush the cut sides of the buns with the remaining 1 tbsp melted butter and toast them cut side down in a dry skillet over medium heat until golden, 1 to 2 minutes. Set aside.

   3 min

   • 1 tbsp unsalted butter
   • 4 brioche buns
6. Step 6

   Turn on your range hood or open a window: blackening smokes. Heat a cast-iron skillet over medium-high heat until it is very hot, about 4 minutes, then add the oil and swirl to coat.

   4 min

   • 1 tbsp vegetable oil
7. Step 7

   Lay the fillets in the skillet without crowding them (work in two batches if needed) and cook without moving them until the crust is dark and set, 3 to 4 minutes. Flip and cook 3 to 4 minutes more, until the fish flakes easily and reaches 135°F at the center. Move to a plate and let rest 3 minutes.

   8 min

   • 4 skinless grouper fillets (about 6 oz each, 1 inch thick)
8. Step 8

   Spread the key lime tartar generously on both halves of each toasted bun. Add a lettuce leaf, a fillet and a good tangle of drained pickled onion. Close the sandwiches and serve right away with lime wedges.

   5 min

   • 4 pieces crisp green leaf or romaine lettuce leaves
   • 1 lime

Where it’s from

Written by AI from an idea

Version 1, saved Oct 5, 2026