Mixed Berry Frozen Yogurt

Puree berries in a food processor until smooth. Transfer to a stainless-steel sieve set over a bowl. Work the puree through the sieve with a spoon to remove seeds. Pour the puree into an ice cube tray and freeze. Slice banana and freeze at the same time.

Combine the frozen berry puree, banana slices and orange-juice concentrate in the food processor. Pulse until coarsely chopped.

Combine yogurt (or buttermilk), brown sugar and vanilla; with the machine running, gradually pour the mixture through the feed tube. Process until smooth and creamy, scraping down the sides of the workbowl once or twice. (The frozen yogurt should be firm enough to be served directly from the food processor, but if it is a little soft, let it harden in the freezer for about 30 minutes.)