Allow egg whites to stand at room temperature for 30 minutes. Meanwhile, line a baking sheet with parchment paper or foil. Draw a 9-inch circle on the paper or foil. Invert paper or foil so the circle is on the reverse side.
Position baking rack in center of oven. Preheat oven to 250 degrees F. For meringue, in a large mixing bowl beat egg whites, salt, and cream of tartar with an electric mixer on medium speed until soft peaks form (tips curl). Add 1 1/2 cups sugar, 1 tablespoon at a time, beating on high speed until stiff peaks form (tips stand straight). Beat in 1/2 teaspoon of the vanilla and 1 teaspoon lemon juice. Sift cornstarch over egg white mixture; fold in gently.
Spread meringue over circle on paper or foil, building up edges slightly to form a shell. Bake for 1 hour (do not open door). Turn off oven; let meringue stand in oven with door closed for 1 hour.
Meanwhile, for pomegranate syrup, in a small saucepan combine pomegranate juice, honey, and 1 tablespoon lemon juice. Bring to boiling over medium heat; reduce heat. Boil gently, uncovered, for 30 to 40 minutes or until mixture is reduced to 1/2 cup. Transfer syrup to a small bowl; cool.
In a chilled large mixing bowl beat whipping cream, 1 tablespoon sugar, and the remaining 1 teaspoon vanilla with chilled beaters of the mixer on medium speed until stiff peaks form (tips stand straight).
Carefully lift meringue off paper or foil and transfer to a serving plate. Spread with the whipped cream. Sprinkle with pomegranate seeds; drizzle with the pomegranate syrup. Top with pistachio nuts.