Put your sliced meat into a bowl and pour 2 tbsp of your olive oil on top. Mix together. If using shrimp: rinse, remove tails, place on paper towels and pat dry.
Combine all your spices in a small bowl and mix together well, then add in with meat and stir to coat.
Add sliced bell peppers and onions and add your remaining 1 tbsp of olive oil on top. Stir so vegetables and meat are all coated well.
Preheat your air fryer at 390 degrees for 5 minutes.
Add half your fajita mixture into basket and spread out so there is little overlap.
Set to 390 degrees for a total of 7 minutes for beef or 5 minutes for shrimp, shake basket halfway thru. If you want your meat to be more well done then just add 1 more minute and check again. Timing will depend on how well done you like your meat and how thick your slices were.
Put in second half of batch and do the same. Then serve inside small tortillas topped with sour cream, avocado, etc...