With the rack in the middle position, preheat the oven to 200°F (100°C). Line a baking sheet with parchment paper.
In a small bowl, dissolve the cornstarch in the vinegar. Set aside.
In a bowl, beat the egg whites with an electric mixer until frothy. Gradually add the sugar, beating until stiff peaks form. Gently stir in the cornstarch mixture.
With a ¼-cup (60 ml) ice cream scoop, form 6 round meringues and place them on the prepared sheet, spacing them evenly. With the back of a spoon, make a shallow well in the centre of each meringue.
Bake for about 2 hours or until the meringue nests are dry and easily peel off the paper. Turn off the oven, and let them dry for about 2 hours, leaving the oven door slightly ajar, using a wooden spoon. Let cool on the baking sheets.
When ready to serve, combine the berries with the sugar in a bowl.
Spoon the double cream into the centre of each meringue nest. Top with the berries.
Double cream has a fat content of 48% and can be found in certain grocery stores or gourmet markets. If unavailable, you may replace the double cream with whipped cream or Greek yogurt.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.