Cornflour and Vinegar: The Pavlova-Style Stabilizer

A French-method meringue made only with egg whites and sugar bakes hard and brittle, which is fine for a pavlova shell but disastrous for a roulade that needs to flex. Adding a small amount of cornflour and an acid (white wine vinegar or cream of tartar) at the end of whisking changes the chemistry: the cornflour absorbs water and slows the protein bonds from over-tightening as the meringue dries, while the acid lowers the pH so the egg-white proteins coagulate more gently. The result is a meringue that bakes long enough to be fully set and food-safe, but stays tender and marshmallow-like inside - flexible enough to roll without splintering. The standard ratio for a 6-egg-white meringue is 1 teaspoon cornflour and ½ teaspoon vinegar, sifted and drizzled over the finished meringue and folded through with a spatula in a few decisive strokes. This is also the trick that lets you give a roulade meringue the longer bake it needs without paying for it in a rubbery interior.