Grate the onion into a bowl. Add the minced garlic, ground cumin, paprika, chilli, lemon juice, oil and the chopped green herbs. Combine well.
Cut the beef steak into 3 cm cubes then put them in a freezer bag. Pour over the spiced mixture, tie the bag and massage the meat to coat each piece well with the marinade.
Chill the bag until you’re ready to cook. (You should marinate for at least an hour, preferably longer).
Pre-soak 8-10 wooden skewers for 30 minutes. Take the meat out of the fridge.
Prepare your grill, BBQ or heat a griddle pan.
Season the beef cubes with salt and pepper, then thread 4-5 pieces onto the skewers. Spray them with a drop of oil.
Cook for about 8-10 minutes, turning the skewers regularly, until they’re cooked to your liking.
Rest for 5 minutes before serving.