Make the marinade: One lime, some olive oil, some garlic, salt, pepper, cumin, coriander and soya sauce in a bowl.
Put the steak into the marinade and leave for several hours in the fridge.
Cook steak on griddle for 4 minutes on each side. Pour extra marinade on each side as it cooks. When done leave to rest.
Heat tortillas in a pan and cut steak into cubes.
Put steak on tortilla and garnish with chopped onion, coriander and lime.