Cracked Sugar Cookies

2 cups white sugar

½ cup butter, softened

½ cup vegetable oil

3 egg yolks

2 cups all-purpose flour

1 teaspoon baking soda

1 teaspoon cream of tartar

1 pinch salt

½ teaspoon vanilla extract

¼ cup white sugar, for rolling

Preheat oven to 300 degrees F (150 degrees C).

Beat 2 cups sugar, butter, and vegetable oil with an electric mixer in a large bowl until smooth. Add egg yolks one at a time, allowing each egg to blend into the butter mixture before adding the next. Sift flour, baking soda, cream of tartar, and salt into the egg yolk mixture; stir. Stir in vanilla extract. Roll the dough into walnut-sized balls.

Spread 1/4 cup sugar onto a flat surface. Roll the balls of dough in sugar to coat. Arrange onto baking sheets spaced at least 2 inches apart.

Bake in preheated oven cooked in the middle, but not yet browned, about 15 minutes.