Keeps 3 days refrigerated. Reheat hard and fast in a hot pan — gentle reheating makes the peppers limp. Freezes 2 months, though the peppers soften noticeably. Store tortillas separately.
Restaurant kitchens use far more heat than a home hob. Get the pan as hot as it goes, dry the chicken first, don't crowd it, and don't stir for the first 3 minutes. Cast iron helps a lot.
Fajita leans on paprika and is milder and smokier; taco seasoning has more chilli and cumin. Interchangeable at a push.
30 minutes in lime, oil and the spices improves it. Beyond about 2 hours the acid starts breaking the meat down and it turns mealy.