Grate the peels of the oranges and grapefruit into a small saucepan. Peel, seed and dice the oranges and grapefruit over the saucepan so that no juice is lost. Add the diced fruit, water, vanilla, cloves, honey, molasses and raisins in a pan. Bring to a boil, then simmer, uncovered for 10 minutes. Cool and chill. Spoon into individual serving dishes and garnish with mint sprigs.