Place the noodles in a bowl and cover with boiling water for 10 minutes or until separated and tender. Drain and set aside.
To make the lime dressing, place the lime juice, sugar and fish sauce in a bowl and stir until the sugar is dissolved. Set aside.
Heat a wok or large non-stick frying pan over high heat. Add the oil, lemongrass, chilli, garlic and ginger and cook for 1 minute. Add the chicken and cook for 3–4 minutes, breaking up any lumps with a wooden spoon. Add the noodles, basil and coriander and cook for 2 minutes or until the noodles are warmed through. Divide between bowls, top with chilli and serve with the lime dressing on the side. Serves 4.