I put frozen berries (usually strawberries, but other berries work too) in a blender or food processor and blend them into sorbet (I add a little lemon juice sometimes and artificial sweetener). If I want more of an icecream or frozen yogurt taste/textre, I add plain or vanilla yogurt. If I'm using the blender I'll add it with the berries, but if I'm using the food processor, because it is small, I'll just do the berries and fold the yogurt in afterward.