Mix together 1 tsp cumin, 1 tsp smoked paprika, 1 tsp chilli powder, 0.5 tsp garlic powder, 0.5 tsp oregano, and 0.5 tsp salt. Toss with 500g lean ground beef.
Heat 1 tbsp oil in a large skillet over medium-high heat. Add the beef and cook, breaking it up with a spoon, for 7–8 minutes until browned. Add 60ml water and stir for 1 more minute.
Char corn tortillas directly over a gas flame for 15 seconds per side, or warm in a dry pan. Keep warm wrapped in foil.
Dice 1 white onion and a handful of coriander. Halve a lime. Slice avocado or make guacamole. Set out salsa and sour cream.
Spoon beef onto tortillas. Top with onion, coriander, a squeeze of lime, and your choice of toppings. Double up the tortillas for sturdiness.