Clean and stew the brains with 1/2 cup of vinegar, 1 sliced onion, salt and pepper. Add a tablespoonful of brown sugar, 1/2 cup of raisins. Let stew until tender. Remove the brains to a platter; add a lump of butter and a tablespoonful of molasses to the sauce; boil up and pour over the brains. Serve cold; garnish with lemon slices.