Beat egg whites and next 4 ingredients at high speed with an electric mixer until soft peaks form (about 5 minutes). Gradually add sugar, 1/3 cup at a time, beating until blended after each addition. Fold in flour. Pour batter into an ungreased 10-inch tube pan.
Bake at 375° for 35 minutes. Invert pan on a wire rack, and let stand 1 hour or until cake is completely cool. Run a knife around cake to loosen edges.