Combine egg whites (at room temperature), cream of tartar, and vanilla; beat until frothy. Gradually add sugar, 1 tablespoon at a time, beating until stiff peaks form. (Do not under-beat the mixture.)
Spoon meringue into 6 equal portions on a well-greased baking sheet. Using back of spoon, shape meringues into circles about 4 inches in diameter; shape each circle into a shell (sides should be about 1 1/2 inches high). Bake at 275° for 55 minutes or until lightly browned. Turn off oven; leave meringues in oven for 1 hour for a crisper meringue. Cool away from drafts. Top with a scoop of ice cream and sliced strawberries.