Preheat oven to 300 degrees fahrenheit. Line a large baking sheet with parchment paper.
Beat egg whites and salt together in the bowl of an electric mixer fitted with the whisk attachment until glossy peaks form.
With mixer running, add sugar in three additions, beating until meringue is stiff and glossy. Fold in cornstarch, ginger, vinegar and vanilla extract.
Spoon about 1/2 cup of meringue mixture onto the prepared baking sheet. Using a spoon, shape the meringue into a circle and with the back of the spoon, create a slight indent in the middle (this will hold the ice cream).
Repeat with remaining meringue mixture, spacing about 2 inches apart.
Place in oven and immediately reduce the temperature to 200 degrees fahrenheit. Bake for 2 hours - the idea is to dry out the pavlova.
Place one ice cream scoop in each pavlova. Drizzle with dulce de leche; sprinkle with crushed gingersnap cookies. Serve immediately.
Cook's tip: to make one 9-inch pavlova, spoon meringue mixture onto center of prepared baking sheet. Spread into a 9-inch circle, making a slight indent in the center to hold the ice cream. Bake as above. To serve, spoon ice cream into center. Drizzle with dulce de leche; sprinkle with crushed gingersnap cookies.