Place fillets in a large shallow dish, such as a casserole dish.
Pour enough milk in dish to cover fish.
Place in refrigerator and soak for 30 to 60 minutes.
When ready to cook, remove fish from refrigerator.
Pour oil into a medium skillet. Place over medium heat.
When oil is hot and shimmering, remove fillets one at a time from milk, allow excess to drip off, and carefully place in hot oil. Add as many as will easily fit in skillet - Do not crowd.
Cook fillet(s) until they flake easily with a fork, roughly about 3 minutes per side.
Remove to a plate and sprinkle with Creole seasoning, salt and pepper, to taste.
Continue with remaining fillets.
Place one fish fillet on the bottom of a bun.
Place a tomato on fillet.
Place a lettuce leaf over tomato.
Spread tartar sauce on top bun and place on sandwich.