Combine the ingredients for the taco spice mix.
Heat a pan over a medium-high heat with half the vegetable oil.
Add the onion and garlic, then cook for 3–4 minutes until softened.
Add the beef mince, breaking it up with a spoon, and cook until browned. Season with sea salt and cracked black pepper.
Stir in the taco seasoning, tomato puree, water and black beans. Reduce the heat slightly and cook for 5 minutes.
Remove from the heat and fold through the avocado and fresh coriander.
Heat a second pan over a medium heat with the remaining vegetable oil.
Place the tortilla into the pan. Sprinkle cheese over one half, spoon over the beef mixture, then top with the remaining cheese.
Fold the tortilla over and cook on both sides until golden and the cheese has melted.
Cut into wedges and serve with lime wedges and sour cream.