Begin by patting your cod fillets dry and removing any bones. Cut into portions.

Set up three shallow dishes: combine flour, salt, pepper, garlic powder, paprika, and optional cayenne in one; whisk eggs and milk in another; place panko in the last dish.

Dredge cod in seasoned flour, dip in egg wash, then coat in panko breadcrumbs.

Place coated fillets on a wire rack to rest for 10-15 minutes.

Prepare tartar sauce by mixing mayonnaise, dill pickle relish, red onion, lemon juice, and optional capers and mustard. Refrigerate for 30 minutes.

Heat vegetable oil in a pot to 350-375°F.

Fry cod fillets in batches until golden brown, about 3-4 minutes per side.

Toast brioche buns lightly in a skillet.

Assemble sandwiches with tartar sauce, lettuce, fried cod, and optional toppings.

Serve immediately with lemon wedges on the side.