Passover Thumbprint Cookies

Ingredients

• 1/2 cup powdered (confectioners) sugar
• 1 cup margarine (2 sticks)
• 2 1/4 tsp vanilla
• zest from 1 lemon
• 1/2 cup matzah cake meal
• 1 1/2 cup potato starch
• 1/4 tsp salt
• fruit preserves such as strawberry, raspberry, apricot