Chinese-Style Peanut Cookie

Preheat oven to 350 degrees F (175 degrees C). Line baking sheets with parchment paper.

Stir together the peanuts, flour, corn flour, and confectioners' sugar in a large bowl until well-combined. Make a well in the center of the peanut mixture. Slowly pour in the vegetable oil and mix with the peanut mixture to make a wet, slightly sticky dough. Pinch off about 2 teaspoons of dough per cookie, and roll into balls about 1/2-inch in diameter. Place the balls on the prepared baking sheets, and brush each with egg yolk, if desired.

Bake in the preheated oven until the cookies are golden brown, 6 to 8 minutes. Let cool on racks.