how long to roast flounder
1 Mix Parmesan cheese, melted butter, mayonnaise, green onions, and 2 tablespoons lemon juice in a bowl; spoon over the fillets. 2  Bake flounder in preheated oven for 10 minutes. 3  Switch oven to broil; broil fillets until the tops are just browned, 3 to 5 minutes.