Heat the oil in a large frying pan or wok over high heat. Cook the chicken, in batches, for 3–5 minutes or until browned, breaking up any lumps with a wooden spoon. Add the garlic and chilli and cook for 1 minute. Stir through the fish sauce, lime juice and sugar. To serve, toss through the cucumber, onion, Vietnamese mint, spearmint and round mint. Serves 4.