1. Preheat grill to high heat.
2. Combine all the patty ingredients except for the fish and let the bread soak up and soften.
3. Meanwhile cut the fish into small chunks and add to the mixture. Form into 6 patties.
4. Place patties onto lightly greased grill grates and reduce heat to medium. Grill 3 minutes on each side.
5. TO MAKE THE TARTER SAUCE: Whisk all the tartar sauce ingredients together. Spread a tablespoon of tarter sauce over the tops of the buns and assemble the burgers in the following order: bottom of the bun, patty, a slice of American cheese, top bun (with tartar sauce.)