Place the yogurt, blueberries and sugar in a blender or food processor and process until smooth.
Press through a strainer to remove seeds.
Stir in the lemon juice and the Kirsch.
Let chill for one hour.
Process according to the instructions with your ice cream maker.
Notes
Yogurt - full fat will give you the creamiest frozen yogurt. Can substitute lower fat, but it won't be as creamy.Kirsch - optional. Can substitute any flavored liquor - Vanilla Vodka works great.