Mix together the berries, sugar, and the juice and zest of orange, tossing to coat. Set aside for 15-20 minutes.
In one of 6 wine glasses or glass bowls, place 1/3 cup cake cubes, 1/3 cup berries and 1/4 cup yogurt, repeat process ending with yogurt. Repeat with the remaining glasses. Refrigerate trifles until ready to serve. Top with a mint if desired. One large trifle can be made if desired.