Heat a large frying pan until medium hot, add the oil, red onion and pepper and stir well. Fry for 2–3 minutes, until just softened. Turn up the heat and add the garlic, cooked pork, cumin ...
Season the beef with pepper. Heat half a tablespoon of the oil in large, non-stick frying pan and stir-fry the beef for 1½ minutes, or until lightly browned but not quite cooked through.