Step-by-step method:

Take an oven dish covered with hot oil and put the onion in it, chopped up finely.

Once it has been cooked a little, add the potatoes, chopped up into thin slices and finally the tomatoes, chopped up into quarters.

Add salt and pepper and the wine and bake until it reduces. When the potatoes start to soften, add the fish, scaled and seasoned with salt and pepper. Place it over the greens and bake it. Sprinkle it with the juice from time to time until it is baked. To serve, cut into roughly 400 g portions for each person.

This recipe has a vegetable base (which you can add other things to, such as peppers, garlic, fennel, etc.) but if you simply want to have it on its own, seasoned only with oil, you'll find it just as tasty.