Preheat the oven to 350 F. Line cookies sheets with parchment paper or a silpat baking mat.
Cream together the sugars, oil, and butter. Add the eggs and vanilla, mixing thoroughly. Blend in the flour, soda, cream of tartar and salt. Stir in the chocolate chips.
Form the batter into walnut size balls and place them onto the prepared cookie sheet. Bake for 8-10 minutes or until set.
Allow the cookies to cool for one minute on the tray before removing them to a cooling rack.
Place baked and cooled cookies in layers separated by waxed paper in an airtight container; cover. Store at room temperature for 3 days or freeze for up to 3 months.
Freezing:There are actually several ways to freeze cookies. I use big plastic containers with lids to store baked cookies in the freezer. Make sure the cookies are completely cooled before layering them between sheets of parchment or waxed paper in the container. The cookies will be good in the freezer for several months -- if you can keep from eating them.