Preheat air fryer to 360 degrees Fahrenheit. Spread about 2 tablespoons of refried beans on one side of a tortilla. Top with about 1/2 cup of cheese. Place another tortilla on top. Lightly brush both sides with oil or spray.
Air fry at 360F for about 4 min on the first side - place the tortilla in the air fryer with the bean side on top otherwise the top tortilla may blow off (this helps it weigh down)! Flip and air fry another 3-4 minutes or until lightly browned and crispy.
Remove the quesadilla and allow it to cool for about 5 minutes. Cut into triangles and serve with salsa and sour cream.
If adding vegetables - add about 1/3 cup of mixed vegetables between the beans and cheese. This is great with a mix of finely chopped bell pepper, green onion, and chopped spinach.
Notes
I used Siete refried beans which have added spices, but Trader Joe's sells them completely plain with no spices.
Added vegetables don't need to be cooked ahead if chopped very small. Then can be pan-cooked for 2-3 minutes if you want them softened a bit.
HYH - Please see the post for details and my "sour cream" recipe. Use mozzarella and TortillaLand or other fresh tortillas.