Preheat the oven to 350°F (use the center rack).

In a large mixing bowl, place 1 cup granulated white sugar, 1 cup powdered sugar, and 1 cup (2 sticks) unsalted butter (room temperature). Use a hand mixer to cream them together on medium speed until light and fluffy, scraping the sides of the bowl as needed (about 2–3 minutes).

Add 3/4 cup vegetable or canola oil and 1 teaspoon vanilla extract to the creamed mixture and mix on low speed until combined, scraping the bowl once or twice.

In a separate bowl, whisk together 4 cups all-purpose flour, 1 teaspoon baking soda, 1 teaspoon cream of tartar, and 1 teaspoon salt until evenly distributed.

With the mixer on low, gradually add the dry ingredients to the wet ingredients and mix just until a cohesive dough forms. The dough may be crumbly but should hold together when pressed; use your hands to press and bring it together if needed.

Portion the dough into 1-inch balls. Roll each ball in the additional granulated white sugar (from the ingredient list) to coat.

Place the sugared dough balls 2 inches apart on an ungreased or lined baking sheet. Flatten each ball slightly with a glass dipped in granulated sugar so the bottom of the glass does not stick to the dough.

Bake in the preheated oven for 15 minutes, or until the cookies are light brown around the edges.

Remove the baking sheet from the oven and let the cookies cool on the sheet for 2 minutes. Transfer the cookies to a wire rack to cool completely.

Once cooled, store the cookies in an airtight container.