Slit the bellies of the cleaned trout. Season to taste well with salt and pepper. In the bellies, place 2 lemon slices each, onion slices, chopped garlic and whole sprigs of parsley.
Arrange the fish in a greased tray atop the other chopped vegetables. Pour the white wine over them, a little oil and cover the tray with foil. Make small holes in the foil and put the fish to bake in a gently warmed oven for about 40 minutes or until ready.
Near the end, you can bake without the foil.