In a large serving bowl, stir together orange sections and pineapple chunks and chill.

To prepare the dressing, combine the chopped mint leaves, sugar, malt vinegar, and water in a foot processor or blender until smooth. Pour the dressing over the oranges and pineapple. Let the dressing mingle with the fruit for at least an hour before serving, overnight if possible.

Garnish the fruit salad with pomegranate seeds and mint leaves, if so desired; and serve cold.