Molho branco com Conceição

Melt 2 Tbs margarine
Add some chopped onion
Add 1 Tbs flour
Add milk.
Add more water or milk if too thick.
Add some generic fish or vegetable seasoning.
Add some parmesan
Stir.

There's your white sauce.

Season your raw tilapia with lime, salt and garlic.
Fry it lightly in a pan with some oil. (Not deep fry).

Pour half the white sauce in the bottom of a 9x13. Place the tilapia organizedly on the sauce.
Cover the tilapia with slices of potato.
Cover the potato and tilapia with white sauce.
Sprinkle with parmesan.
Bake for 30 minutes or until cooked.