Preheat oven to 350 degrees. In medium bowl, beat egg yolks; stir in condensed milk, lemon juice and rind. Turn into shell. In small bowl, beat egg whites with cream of tartar until foamy; gradually add sugar, beating until stiff but not dry. Spread meringue on top of pie, sealing carefully to edge of shell. Bake 15 minutes or until meringue is golden brown. Cool. Chill before serving Refrigerate leftovers.
