Heat the oil in a wok or large frying pan. Stir-fry the garlic and chillies over a medium heat for 1–2 minutes or until the garlic has lightly browned. Add the chicken and onion and stir-fry for 4–5 minutes or until the chicken is cooked.
Add the rice and fish sauce and stir-fry for another 3–4 minutes. Taste and adjust the seasoning. Add the basil leaves and stir-fry until the basil begins to wilt.
Spoon on to 4 warm serving plates.