You'll need to cut the pork shoulder into fairly even strips - you might be able to get 3-4 strips in total.
Mix the marinade ingredients together - so using a large container or dish, combine the soy sauce, hoisin sauce, garlic, brown sugar, five spice, pepper, salt, honey, and red food colouring [if you're using], together.
Add the pork pieces, and make sure all the meat is covered in the marinade. Cover with clingfilm then put in the fridge and marinate for at least 12 hours - the longer the better, I like leaving it for 24 hours. If you get a chance, turn the meat over in the sauce at least once during the marinating time.
Once you're ready to air fry the char siu pork, brush the air fryer basket with oil or spray (to prevent the pork from sticking), preheat the air fryer for 5 minutes at 205°c.
Reserve the marinade and set it to one side.
Transfer the pork strips to the air fryer basket, making sure there is space between the strips. You may need to do a couple of batches if your basket isn't big enough.
Set the air fryer to 200°c for 20 minutes. And brush extra marinade on top of the pork.
Every 5 minutes, turn the pork and brush more marinade on the top each time you turn the pork over.
After 20 minutes the pork should have a lovely shiny glaze and be thoroughly cooked. If you feel it needs a little longer, you can air fry for a further 5 minutes.
Slice into pieces and serve over rice or noodles with green vegetables.