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 become translucent.

Add the minced garlic and cook for another minute until fragrant. Be careful not to let the garlic burn, as it can become bitter.

Turn the heat up to medium-high, add the ground beef mince to the pan, and break it up with a wooden spoon. Cook for 6-8 minutes, stirring frequently, until the beef is browned all over. You want to get some nice caramelisation on the meat, as this is where a lot of flavour comes from.

Drain off any excess fat from the pan. Return the pan to the heat and add the smoked paprika, ground cumin, dried oregano, chilli powder, salt, and pepper. Stir everything together and cook for 1 minute to toast the spices and release their aromas.

Stir in the tomato purée, ensuring it coats the beef well. Pour in the beef stock (or water), give it a good stir, and bring the mixture to a gentle simmer.

Reduce the heat to low, cover the pan, and let it simmer for 10-15 minutes. This allows the sauce to thicken and the flavours to meld beautifully. I find that this simmer is the secret to a really rich filling. Remove the lid for the last few minutes if you'd like the sauce to be thicker.

While the beef is simmering, prepare your toppings. Grate the cheese, shred the lettuce, dice the tomatoes, and get your sour cream and jalapeños ready.

Warm your taco shells or tortillas according to the package instructions. I like to warm soft tortillas in a dry frying pan for about 30 seconds per side.

Assemble your tacos! Spoon a generous amount of the ground beef filling into each shell, then let everyone add their own favourite toppings. Serve immediately.