Preheat oven to 400°F. Grease jelly roll pan with shortening. Sprinkle well with cake flour, shaking off loose flour.
Separate eggs; Beat yolks 1 minute. Add pinch of salt to egg whites, then beat until foamy.
Add cream of tartar and continue beating whites until they cling to bottom and sides of bowl, then beat 1 minute longer.
Fold beaten egg yolks into egg whites gently but quickly. Fold in sugar, flour and vanilla. Do not over mix.
Pour batter into pan, spreading evenly from center out with a spoon.
Tap pan several times on table to break any air bubbles and bake in center of oven 10-12 minutes. Loosen sides and bottom. Turn out of pan onto a dry towel.
Cool 10 minutes, then trim crusty edges. Roll loosely in a towel and cool on rack before decorating.