Combine oleo, oil, sugar, and egg in a mixing bowl.

Add vanilla extract and mix well.

In a separate bowl, whisk together flour, soda, and cream of tartar.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Roll the dough into small balls.

Dip a glass in sugar.

Flatten each dough ball with the sugar-dipped glass.

Place the flattened cookies on ungreased cookie sheets.

Bake in a preheated oven at 375°F (190°C) for 8 to 10 minutes, or until lightly golden.

Let the cookies cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.