Place wax paper on cookie sheet (or just grease a cookie sheet) and dust it with powdered sugar and cornstarch. Beat egg whites until stiff, then slowly add the sugar, beating until stiffer. Fold in corn starch, cream of tarter, vinegar, and vanilla. Pile high on cookie sheet and 7-8 inches across. Bake for 1 hour. OR, cook in several circles and cook 30-45 minutes. Do not allow to color on top. Cool, then spread with whipped cream and fruit. Leave door open after cooking until pavlova cools.