Add beef, onion, bell pepper, seasonings & stock to the slow cooker.
Cover & cook on low 6-8 hrs.
Heat tortillas in a tortilla warmer for 1-2 minutes in the microwave.
Once cooked, spoon 2-3 tbsp of cooked cheesesteak in the center of the tortilla- lengthwise across the tortilla.
Add a little cheese (amount is a personal preference, but I like to use about 1/4 of a slice per taquito)
Roll tortilla tightly & place in air fryer basket.
Repeat with all tortillas.
Brush lightly with oil or spray with cooking spray.
Cook in a preheated air fryer at 350 degrees for 6-8 minutes, or until lightly browned (flip halfway through & add more oil).