Pre-heat the oven to 275°F.
Line a baking tray (or a special pavlova pan, if you have one) with grease proof paper (or grease it and dust it with confectioners sugar).
Lightly beat the egg whites, then add half the sugar and beat the mixture to a stiff-peak consistency.
Fold in the cornstarch, vanilla, vinegar and remaining sugar.
Pile the beaten mixture on to the pan in whatever shape you like.Bake for 1 1/2 hours, until light brown.
Cool it in a draught-free place to avoid sinking.