Preheat oven to 325 degrees. Place large piece of aluminum foil on large baking sheet. Set the flounder fillets on the aluminum foil with the edges curled up to keep juices from spilling. Brush fillets with olive oil or unsalted butter and then season with salt and black pepper.
In small mixing bowl add bread crumbs, lemon zest, and chopped basil. Add about a teaspoon of olive oil or butter to add some moisture and mix well. Top flounder fillets with bread crumb mixture. Spread lemon juice around base of each fillet to keep flounder from drying out while cooking.
Bake in the oven for approximately 15 minutes or until bread crumbs are golden brown and fish flakes easily.