Peel 1-1,5 kg of onion and finely chop them into cubes. Fry them in oil and add a little bit of water. When the onions are golden and glassy, pour them into a ceramic form.
Mix 1 cup of water, 2 spoons of flour, 1 spoon of red ground pepper and a little bit of Cayenne pepper (hot), and a few fresh mint leaves, and pour it over the onions. Fry some fish fillets in a pan with some salt and lay them on top of the onions.
Put the form in the oven and bake it until it is nicely brown.
The water and spice mixture will create a nice sauce.