Allow egg whites to stand at room temperature 30 minutes (this helps create more volume). Meanwhile, line a baking sheet with parchment.
Preheat oven to 250 degrees F. For meringue, in the bowl of a stand mixer fitted with the whisk attachment* beat egg whites, cream of tartar, and salt on medium speed until soft peaks form. Add the 1 1/2 cups sugar, 1 Tbsp. at a time, beating on high speed until stiff peaks form and meringue is no longer gritty (18 to 20 minutes), scraping down bowl as needed. Beat in lemon juice and orange water. Using a rubber spatula, gently fold in cornstarch.
Spoon meringue mixture into 8 large mounds (about 3/4 cup each) on a parchment paper-lined very large baking sheet, spacing them 3 inches apart. Using the back of the spoon, create an indent in each meringue. Bake for 1 hour. Turn off oven; let meringue dry in oven with the door closed for 1 hour. Remove and cool completely.
In a bowl toss berries with the 1 Tbsp. sugar. Let stand 20 minutes.
Fill each shell with 2 tablespoons purchased lemon curd and top each with berries and mint leaves.