Remove from the oven, allow to cool slightly and pour off any fat from the tin. Cut a piece of cardboard so it fits snugly inside the tin and wrap it in foil. Use the cardboard as a lid, and top with several tins to weigh the terrine down as it cools – this will give the terrine a tight, firm texture. Once cool, chill overnight, still weighted down. Slice and serve with toast, cornichons, pickled onions, mustard and onion chutney.