1. Sift together in a large bowl: flour, sugar, baking soda and salt. Combine orange and peel, oil, vinegar and vanilla. Add to dry mixture. Stir until smooth.
2. Line pan(s) with wax or parchment paper, rub in Crisco. Pour batter in pan(s). 
3. Heat oven to 350F°. If using one 8″ x 8″ pan, bake for 35 minutes. If using 2 – 9″ round pans, bake for 25 minutes. Let cool in the pan(s) for 10 minutes.
3. Slide a slim knife around the cake to detach it from the pan. Invert the cake and peel off the paper liner. Let cool right side up on the rack. Serve dusted with powdered sugar or with icing.