Toss the chicken strips with a little oil, the juice of a lime and the fajita seasoning. Season with salt and freshly ground pepper.
Heat a frying pan and fry the chicken in a splash of oil until lightly browned.
Add the onion and toss with the chicken, then add the pepper strips. Let it all fry for about 5 minutes, then stir in the parsley. Season to taste with salt and freshly ground pepper.
Meanwhile, warm the tortillas as described on the packet.
Spread the tortillas with guacamole and top with the fajita chicken. Serve with crème fraîche and chilli sauce.