2 lbs. flounder fillets, thawed
2 tbsp. lemon juice
1 onion, sliced thin
1 1/2 c. mayonnaise
1/3-1/2 c. Parmesan cheese

Rinse and pat dry flounder. Brush with lemon juice and arrange slices of onion on top. Mix mayonnaise and cheese and cover each fillet. Cover and bake under broiler for 15 minutes. Remove foil and continue broiling until brown, about 5 minutes.