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In a stand mixer fitted with the whisk attachment, beat egg whites, cream of tartar, and salt on medium speed until soft peaks form. Gradually add 1 1/2 cups sugar, 1 tablespoon at a time, beating on high speed until stiff peaks form and the meringue is no longer gritty, scraping the bowl as needed. Beat in the lemon juice and rose water, then gently fold in cornstarch.