Sauté the Aromatics: Heat the olive oil in a large, heavy-based frying pan or skillet over a medium heat. Add the finely chopped onion and cook for 5-7 minutes, stirring occasionally, until it has softened and turned translucent. Add the minced garlic and cook for another minute until fragrant.

Brown the Beef: Increase the heat to medium-high, add the minced beef to the pan, and break it up with a wooden spoon. Cook for about 6-8 minutes, stirring to break up any clumps, until the beef is browned all over. For a really good browning, it's important not to overcrowd the pan. You can learn more about the science of browning meat, known as the Maillard reaction, to understand why this step is so crucial for flavour.

Drain the Fat: Once browned, tilt the pan carefully and spoon out any excess fat. This step is key to a rich but not greasy filling.

Bloom the Spices: Add the chilli powder, smoked paprika, ground cumin, dried oregano, and cayenne pepper (if using) to the pan with the beef. Stir continuously for about 1 minute. What works best for me is to toast the spices directly in the pan like this; it really wakes up their essential oils and makes the filling much more aromatic.

Create the Sauce: Stir in the tomato purée and cook for another minute. Pour in the beef stock, add the light brown sugar, and season generously with salt and pepper. Stir everything together until well combined.

Simmer to Perfection: Bring the mixture to a gentle boil, then reduce the heat to low. Let it simmer for 10-12 minutes, stirring occasionally, until the sauce has reduced and thickened nicely. It should coat the meat beautifully.

Warm the Tacos: While the beef is simmering, prepare your taco shells according to the package instructions. I usually warm soft tortillas in a dry frying pan for 30 seconds per side or heat hard shells in the oven at 180°C (160°C fan) for a few minutes until crisp.

Assemble and Serve: Spoon the hot beef filling into the warm taco shells. Set out bowls of grated cheese, shredded lettuce, diced tomatoes, soured cream, and fresh coriander, and let everyone build their own tacos. Serve immediately with fresh lime wedges on the side for squeezing over.