PREP: Drain the beans. Chop peppers and onions into strips. Crush garlic. Chop cilantro. Slice avocado (or you can wait and slice at the end).
STEP 1
To make the fajita mix, heat the oil in a pan and fry the pepper strips and the onion until soft and starting to brown at the edges. Add the garlic and cook for 1 min, then add the spices and stir. Use more spices for a stronger flavor. Cook for a couple of mins more until the spices become aromatic, then add half the lime juice and season. Transfer to a dish, leaving any juices behind, and keep warm.
STEP 2
Tip the black beans into the same pan, then add the remaining lime juice and plenty of seasoning. Stir the beans around the pan to warm them through and help them absorb any flavours of the fajita mix. (If you want to expedite things, you can cook them in a separate pan at the same time.)
STEP 3
Warm the tortillas, then serve with the fajita mix, beans, avocado and sour cream.
You can make gluten-free by subbing out the flour tortillas for a different kind, or put over greens or rice.