1. Preheat oven to 350°. Beat egg whites and salt at high speed with an electric mixer until foamy. Beat in vanilla and lemon juice. Add cream of tartar; beat until soft peaks form. Add sugar, a few tablespoons at a time, beating until firm peaks form. Fold in flour, 1/4 cup at a time. Fold in coconut and lemon zest.
2. Spoon batter into an ungreased 10-inch tube pan, spreading evenly. Cut through batter with a knife to break air pockets. Bake 27 minutes or until cake springs back when lightly touched. Invert pan; cool completely.
3. Loosen cake from sides of pan, and invert onto a plate. Drizzle with Caramel-Orange Sauce; top with Candied Lemons, if desired.