Meringue
Process sugar and cornstarch together in a food processor. In a clean bowl, whip the egg whites to stiff peaks. Add ½ cup of the sugar-cornstarch mixture and whip again to stiff, glossy peaks. Fold in the remaining sugar-cornstarch mixture, vinegar, and vanilla. Place in a pastry bag with a large tip or a plastic bag with a corner cut off.

Preheat the oven to 300°F. On parchment paper, draw 4-inch circles about 1½ inches apart: You will fit 6 on a large sheet pan. Turn the paper pencil side down on a large sheet pan. Pipe a flat circle spiral on each circle, starting on the outside edge. Then spoon or pipe the remaining meringue in rough swirls to form a basket. You should have 8 to 10 depending on the size.

Bake in the oven for 1 hour. Turn off the oven and let cool in the oven. The inside may be crisp or soft depending on the humidity. Carefully remove the baskets from the paper and store in an airtight container until ready to use, up to 7 to 10 days.

Pavlova With Raspberry Coulis
Make the raspberry sauce by cooking the jam, water, and 1 tablespoon of the sugar in a saucepan over medium heat for 5 to 10 minutes. Whip the cream to heavy peaks and fold in 1 tablespoon sugar and the Grand Marnier. Spoon the whipped cream into the meringue basket, spoon on the raspberry sauce, top with fresh raspberries, and serve immediately.