Mix oil, butter, brown sugar, and sugar using a mixer.
Add egg and vanilla. Mix thoroughly.
Add milk to baking soda in a separate small bowl.
Mix cream of tartar, flour and salt in another separate bowl.
Add milk mixture alternating with flour mixture to mixing bowl. Mix thoroughly.
Stir in remaining ingredients except colored sugar sprinkles.
Place in refrigerator for 2 - 3 hours or overnight.
Preheat oven to 350 degrees and pour the colored sugar into a bowl.
Roll the dough firmly into walnut sized balls, dip tops into colored sugar, and place on cookie sheets. Flatten each cookie slightly.
Bake at 350 degrees for 7-8 minutes until lightly browned.
Cool 1 - 2 minutes on baking sheets, and then remove to cooking racks.