Preheat the oven to 300°. Line a baking sheet with parchment paper. Using a plate as your guide, draw an 11-inch circle on the paper. Turn the paper over.
In a large heatproof bowl, combine the egg whites, sugar and cream of tartar. Set the bowl over 1 inch of simmering water and stir constantly until the whites are very warm and the sugar is completely dissolved, about 5 minutes.
Remove from the heat. Using an electric mixer, beat the egg whites until they form stiff, glossy peaks. Transfer the meringue to the outlined circle and use a rubber spatula to shape it into a wide-rimmed bowl with a 1-inch-thick base. Bake for 15 minutes. Reduce the oven temperature to 250° and bake for 1 1/2 hours longer, or until the meringue is light brown and crisp. Let cool completely.
Carefully lift the bowl off the paper and transfer to a platter. Fill with scoops of the sorbet and berries and serve at once.