Miniature Grapefruit Souffles with Ginger

Name: Miniature Grapefruit Souffles with Ginger
Ingredients: Unsalted butter, room temperature, for ramekins; 1 3/4 cups grapefruit juice (from about 3 red grapefruits); 1 tablepoon finely grated fresh ginger; 1/2 cup granulated sugar, plus more for dusting; 1 teaspoon finely grated red-grapefruit zest; 5 large egg yolks, room temperature; 2 tablespoons cornstarch; 2 tablespoons all-purpose flour; 1/4 cup plus 2 tablespoons Greek yogurt; 9 large egg whites, room temperature; Pinch of coarse salt; Pinch of cream of tartar; Confectioners' sugar, for dusting