Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a large mixing bowl, combine the peanut butter, granulated sugar, and vegetable oil. Mix until smooth and well combined.
Add the egg, vanilla extract, baking soda, and salt to the peanut butter mixture. Stir until all ingredients are fully incorporated and a dough forms.
Using a tablespoon or cookie scoop, scoop dough and roll into balls about 1 inch in diameter. Place them on the prepared baking sheets about 2 inches apart.
Flatten each dough ball gently with a fork, creating a crisscross pattern on top.
Bake in the preheated oven for 10 to 12 minutes, or until the edges are lightly golden.
Remove from oven and let the cookies cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.