Preheat oven to 275°.
Cover a large baking sheet with parchment paper. Draw a 10-inch circle on parchment paper. Turn parchment paper over. Secure with masking tape; set aside.
Beat egg whites at high speed of a mixer until foamy. Add salt, beating until stiff peaks form. Gradually add sugar, 1 tablespoon at a time, beating until stiff peaks form (do not underbeat). Sprinkle cornstarch over egg white mixture; beat at low speed until well-blended. Stir in vanilla and vinegar.
Spoon egg white mixture onto drawn circle. Using the back of spoon, shape meringue into a "nest" with 2 1/2-inch sides. Bake at 275° for 2 hours or until dry. Turn oven off; let meringue cool in closed oven at least 12 hours. Carefully remove meringue from paper; set aside.
Combine fruit and powdered sugar; let stand 5 minutes. Combine ice cream and liqueur. Spoon fruit mixture onto meringue, and drizzle sauce over top.