Heat vegetable oil in small skillet on medium heat until hot. Place 1 tortilla into hot oil. Using tongs, quickly flip tortilla to the other side and then transfer it onto paper towels to absorb excess oil. NOTE: Do not fry the tortilla... simply let it get coated on both sides with hot oil and then remove it! Continue until all the tortillas have been heated in the oil. Pat each one dry before filling.

Use ovenproof pan that fits in your air fryer basket. Spread ¼ cup of enchilada sauce on the bottom of dish until covered. NOTE: If your air fryer has a "preheat" function, preheat to 350°F. in order to save time.

Fill one tortilla at a time with ¼ of the grated cheese down the middle of the tortilla. Sprinkle ¼ of the onions on top, then spoon a little bit of remaining enchilada sauce in a line on top of cheese/onions. TIP: Reserve small amount of onions/cheese to sprinkle on top of enchiladas before they're cooked! Roll one side of the tortilla up and over the filling fairly tightly. Place enchilada SEAM SIDE DOWN on top of sauce in the dish.

Pour remaining enchilada sauce evenly over enchiladas, to cover. Top enchiladas with reserved onions and cheese.

Air fry enchiladas for 7-8 minutes at 350°F (check them at 7 minutes). When done, sauce should be bubbly around edges, and cheese should be fully melted.

Carefully remove dish out of the air fryer basket using hot pads. Let enchiladas cool for a minute before serving. Garnish with fresh cilantro leaves, dollops of sour cream or guacamole (optional). Serve and enjoy!