Wash and dry the trout. Remove the heads and tails of the fish, you could use them to make fish stock, but only freeze them if the fish was fresh, do not freeze already defrosted fish again. Cut the fish into 5-6 cm/ 2-2.4 inches pieces.

Heat 1 tablespoon of the olive oil in an ovenproof pan. Coat the fish pieces with flour, shake off the excess and fry the fish in the pan, about 2 minutes on each side.

In the meantime, halve the onions and slice the halves thinly.

Remove the fish from the pan and set aside.

Add the remaining oil to the pan, add the onions and ½ teaspoon salt. Cook on low heat for about 10 minutes, stirring often, or until the onions are translucent but still uncolored. Stir well and often.

In a small bowl whisk together the water, tomato paste, and sweet white wine (and the sugar if you are using dry white wine). Add the mixture to the pan together with the chopped garlic, bay leaf, peppercorns, lemon juice, and salt to taste. Mix well.

Add the fish pieces and place the pan in the preheated oven.

Cook for about 15 to 20 minutes. Sprinkle with chopped parsley.

Serve hot with polenta or boiled potatoes or leave to cool and serve at room temperature with crusty white bread and a glass of white wine.