Preheat oven to 300 degrees. Using an 8-inch bowl as a guide, trace the perimeter of the bowl onto a sheet of parchment paper. Transfer parchment paper, pencil side down, to a baking sheet. Set aside.
In the bowl of an electric mixer fitted with the whisk attachment, beat egg whites and salt together until glossy peaks form. With mixer running, add sugar in three additions, beating until meringue is stiff and glossy. Sprinkle in cornstarch, vinegar, and vanilla; gently fold to combine.
Mound the meringue in the center of the 8-inch circle. Using a spatula, evenly spread meringue out towards the edges. Transfer baking sheet to oven and immediately reduce the temperature to 250 degrees. Bake for 1 hour and 15 minutes.⏱ 75 min
Turn off oven and let meringue cool completely in oven. When meringue is cool and completely dry, top with whipped cream and desired fruits.