Beat egg whites at medium speed for one minute. Turn speed up to high and gradually add sugar, beating for 10 minutes, or until stiff peaks form.
Gently fold in vinegar and vanilla.
Gently fold in cornstarch, just until well blended.
On parchment lined baking sheet pipe into 4 inch circles.
Make a well in the center of each with the back of a spoon.
Bake at 225F degrees for 1 hour, 15 minutes. Turn oven off and leave in additional 20-30 minutes.
Cool completely, and then fill well with whipped cream and top with berries or other fruit.