1. In a bowl, use a potato masher or fork to finely crush peaches with sugar.
2. Add yogurt, lemon juice, and vanilla and mix well.
3. Nest bowl in ice water and stir often until mixture is cold, about 5 minutes.
4. Pour yogurt mixture into an ice cream maker (1-qt. or larger capacity). Freeze according to manufacturer's directions until mixture is firm enough to scoop or dasher is hard to turn or stops.
5. Serve softly frozen, or freeze airtight ( see below).
Firming and Storing Ice Cream:
To get frozen desserts hard enough to scoop onto a cone, or to store them, transfer when frozen to an airtight container and put in the freezer at least 3 hours or up to 1 week.
If freezing with ice and salt, leave the frozen dessert in ice and salt up to 3 hours.
For best flavor and texture, serve frozen desserts within a week. On longer standing, icy crystals develop.
Nutritional analysis per 1/2 cup.