How to make
Clean the fish and cut it into thick slices. Drizzle it very lightly with lemon juice.
Cut the onion into crescents, rub it with a pinch of salt. Heat a cup of olive oil in a pan, add the chopped onion and two bay leaves. Cover the dish, stew the vegetables until they soften.
In a baking pan pour the grinded tomatoes and add two tablespoons of the tomato concentrate. Season with salt, ground black pepper and a few peppercorns. Add the stewed onion and stir the sauce.
Arrange the mackerel in the baking pan. Add a handful of olives.
Bake the dish at 390°F (200 degrees) in a preheated oven for about 40 minutes.
Serve the mackerel with olives with lemon slices.
Enjoy!