Mix all the ingredients for the sauce in a small bowl and put to one side.
Heat some oil in a wok or heavy-based frying pan and stir-fry half the garlic until just turning golden.
Increase the heat, add half the beef and half the chillies and stir-fry for 2–3 minutes until the beef is cooked. Using a slotted spoon, remove the garlic, beef and chillies an