Heat the oil in a wok over a high heat until smoking, then add the garlic, shallots, chillies and ginger or galangal. Stir fry until the garlic is lightly browned.
Add the chicken and fry, breaking up lumps, until it is opaque and cooked through.
Add the basil, stir to mix, then add the fish sauce and sugar. Stir again for a minute or so to mix well.