Clean the bonito from its gills, guts and the red stripe on the spine. Soak it for 2-3 hours in a mixture of 4 1/5 cups (1 liter) of water and 2 cups (500 ml) of vinegar with a little salt. Then rinse it under running water.
Stew the cleaned onions in hot oil, then add the whole or halved cloves of garlic, top up with the wine and bay leaf, a little salt and pepper, finely chopped crushed tomatoes and parsley. Place the bonito in a greased oven dish. Arrange the peeled and sliced potatoes around it and pour the sauce over them.
You can arrange lemon slices on the bonito. Put the dish to bake in a preheated 392°F (200 °C) oven until ready.