Combine flour, salt, pepper and garlic powder. Dust fish with flour mixture. Heat oil in a large oven-safe skillet over medium-high heat. Lightly brown fish on both sides. Top each piece of fish with onion, tomato, half of chile pepper and cheese. Place under a broiler, about 6 inches from the heat, unless cheese melts. Combine mayonnaise with Tabasco and lemon juice. Spread mayonnaise mixture on buns. Put lettuce on buns and place fish portion in each bun.