Preparation
Cream butter; gradually add sugar, beating at medium speed of an electric mixer until well blended. Add lemon rind, lemon juice, and next 3 ingredients; beat well. Combine flour, baking soda, and cream of tartar; gradually add to creamed mixture, beating well. Add oats; mix well.
Drop dough by rounded teaspoonfuls onto cookie sheets coated with cooking spray. Bake at 350 for 12 minutes. Cool on wire racks.