Heat the pan and cook the onion. Place a large frying pan over medium-high heat and add the olive oil. Once the oil shimmers and moves easily across the pan surface, add the diced onion. Cook for 3-4 minutes, stirring occasionally, until the onion turns translucent and softens, releasing a sweet, fragrant aroma.

Brown the beef mince. Add the beef mince to the pan, breaking it apart with a wooden spoon. Let it sit undisturbed for 60 seconds to develop a deep brown crust on one side, then stir and continue breaking it into small pieces. Cook for 5-6 minutes total until no pink remains and you hear a steady sizzle. The meat should look uniformly brown, not grey.

Add the garlic and spices. Push the beef to one side of the pan and add the minced garlic to the empty space. Cook for 30 seconds until fragrant, then stir everything together. Sprinkle the cumin, smoked paprika, oregano, chilli powder, salt, and pepper over the meat. Stir well for 1 minute until the spices coat every piece of beef and the kitchen fills with a warm, toasty fragrance.

Incorporate the tomato paste. Spoon the tomato paste into the centre of the pan and stir it into the meat mixture. Cook for 2 minutes, stirring constantly. The paste will darken slightly and cling to the beef, creating a rich, concentrated base. You'll notice the colour deepen from light brown to a deep reddish-brown.

Pour in the beef stock. Add the beef stock and stir to combine, scraping the bottom of the pan to lift any browned bits. Let the mixture simmer for 3-4 minutes until the liquid reduces by about half and the beef looks moist but not soupy. The texture should be thick enough to hold its shape on a spoon without excess liquid pooling around it.

Warm the taco shells. While the beef simmers, heat your taco shells according to package directions. For hard shells, place them on a baking tray and warm them in a 180°C oven for 5 minutes until they feel crisp and release a warm corn aroma. For soft tortillas, warm them in a dry pan for 30 seconds per side until they develop light brown spots and become pliable.

Rest and assemble. Remove the beef from the heat and let it rest for 2 minutes. This brief pause allows the juices to redistribute into the meat rather than pooling at the bottom of the pan. Spoon the beef into the warm shells, then let everyone add their preferred toppings.