1 (6 1/2 or 7 oz.) can tuna, drained & flaked
1/4 c. fresh bread crumbs
1/4 c. ketchup
3 tbsp. onion, chopped
1 egg, lightly beaten
2 tsp. lemon juice
1/2 tsp. dry mustard
1 1/2 c. Sharp Cheddar cheese, shredded
1 (8 1/2 oz.) pkg. corn muffin mix, prepared according to package directions

Preheat oven to 350 degrees. Lightly grease a 9-inch round cake pan. In a bowl, combine tuna, bread crumbs, ketchup, onion, egg, lemon juice and mustard. Spread in bottom of pan and sprinkle shredded cheese on top. Drop spoonfuls of corn muffin batter on top of cheese, then spread gently to cover. Bake for 25 to 30 minutes, or until golden brown. Cool in pan for 5 minutes. Run a sharp knife around inside edge of pan and invert onto serving plate. Garnish with tomato slices, if desired. Cut into wedges and serve immediately. Makes 6 servings.