Granny Bloedel said she got this recipe from her grandmother in Darmstadt, Germany. When my brother was living in south Texas, he went to the store to buy a 'Schaum Torte Pan' and they had no idea what he was talking about. We later learned that the rest of the world calls it a 'spring form pan.'
Gradually add the sugar and continue beating until the egg whites are stiff.
Add the 1Tbs white vinegar and 1tsp vanilla.
Spoon into the greased spring form pan and bake at 325 degrees for 50-60 minutes. Serve with vanilla ice cream and fresh pureed strawberries. It's like a meringue that is crisp on the outside but soft and spongy on the inside.