In a large mixing bowl, whisk together all-purpose flour, baking powder, baking soda, and salt.
In a small bowl, mix warm water with vanilla extract, canola oil (or your choice of oil). Gradually stir this liquid into the dry ingredients until combined.
Knead the dough on a lightly floured surface for 7 minutes until smooth and elastic, or use a stand mixer on medium speed with a dough hook for 4 minutes.
Divide the dough into small balls, about 2-3 tablespoons each, roughly the size of golf balls. Place them on a lightly floured tray, cover with a clean kitchen towel, and let them rest for 10 minutes to relax the gluten.
Roll out each dough ball on a lightly floured surface into a thin circle, about 5 inches (13cm) round.
Heat oil in a deep, heavy-bottomed pot to 350°F (175°C). If you don’t have a frying thermometer, test the oil's readiness by dropping in a small piece of dough; it should sizzle and float.
Fry each rolled-out dough circle in the hot oil until golden brown and crispy, about 1 minute per side.
Remove the buñuelo from the oil and drain on a wire rack suspended over a baking pan.
For the cinnamon sugar topping, mix sugar and cinnamon in a shallow bowl. Roll the warm buñuelos in this mixture.
Serve your Mexican buñuelos warm, coated in sweet cinnamon sugar.