Mix the tartar sauce together and set aside.
Put the flour in one shallow dish, the egg and salt in another, and the bread crumbs in a third.
Mix the egg and salt together with a fork until well blended.
Dip each piece of fish into the flour and coat both sides, then into the egg and coat both sides, then into the bread crumbs, pressing down lightly so the bread crumbs adhere.
Heat a bit of oil in a large skillet. You don't need tons...maybe 1/4" in depth.
Cook each fish filet about 3 minutes on each side, depending on thickness. Poke with a fork and you should be able to feel when they're cooked through. Cook in batches rather than crowding the fish.
Remove to a paper towel lined plate.
Toast the buns and add a piece of fish to each. .
I usually let everyone make their own sandwiches at the table so they can add whatever sauce and condiments they want.