Position a rack in the lower third of an oven and preheat to 250 degrees.

Draw a 9-inch (23-cm) circle on a sheet of parchment paper. Turn the parchment over and place on a baking sheet.

In the bowl of an electric mixer fitted with the whisk attachment, beat the egg whites on medium speed until well combined for about  1 minute.

Sprinkle the cornstarch over the egg whites and beat until foamy, about 3 minutes.

Increase speed to high and gradually add 1 cup of sugar.

Beat for 8-10 minutes until stiff, shiny peaks form. Blend in the vanilla and the lemon juice.

Spread the meringue inside the circle on the parchment. Use the back of a large spoon to create an indentation in the center of the meringue and a slight rim around the edges.

Bake until the meringue is crisp and the color has deepened slightly, about 1 hour.

Turn off the oven and, leaving the door closed, let the meringue cool in the oven for at least 2 hours or up to overnight. Carefully remove the meringue from the parchment paper and place on a serving platter.

Stir the berries with 1 tablespoon of the sugar. Set aside.

In the clean bowl, beat together the cream, remaining 2 tablespoons sugar and the remaining 1 teaspoon vanilla until soft peaks form. Spoon the whipped cream into the hollow of the meringue and top with the berries.