Combine flour,cream of tartar, baking soda, and salt and set aside.
Mix together sugar, powdered sugar, butter and vegetable oil and beat well in a standard mixer. Add eggs and beat again.
Carefully add flour mixture. . Mix in vanilla extract. Drop small balls of dough on parchment lined cookie sheet. Can add sugar on top at this point, I like them plain. Bake at 350 for 10 minutes or until lightly golden.