Cut the pork belly roughly into 1 cm chunks. Heat half of the butter in a pan and gently cook the onion, garlic and pork belly for 3-4 minutes, turning every so often. Dust with the flour, stir well, then gradually stir in the wine and fish stock. Simmer gently for about 45 minutes.
Season the cod’s tongues lightly with salt and pepper. Heat the rest of the butter in a frying pan and fr