Step 1

Heat the oil in a large flameproof baking dish over medium-high heat. Add the beef and onion. Cook, using a wooden spoon to break up any lumps, for 8 minutes or until the beef is browned and onion softens. Meanwhile, place the sweet potato in a microwave-safe bowl. Microwave, covered, on High for 5 minutes or until just tender. Drain

Step 2

Scatter the taco seasoning and oregano over the beef mixture. Cook, stirring, for 1 minute or until aromatic. Add the tomatoes, black beans and sweet potato. Bring to the boil. Reduce heat to medium and simmer for 5 minutes or until the beans are heated through and the liquid reduces slightly.

Step 3

Preheat grill on high. Scatter the cheese over the beef mixture and grill for 5 minutes or until the cheese is melted and golden. Season and sprinkle with the coriander and shallot to serve.