Heat a little oil in a large frying pan or wok. Add cumin and beef. Increase the heat to medium high and cook, stirring often until the beef is really well browned.

Add the chillies and stir fry for another minute.

Remove from the heat and add the soy and vinegar. Taste and season with extra soy and/or vinegar as needed. Serve with coriander (cilantro) leaves on top.