Cover noodles in cold water and soak until tender. Drain. Wash coriander and finely chop roots and stems. Reserve leaves for garnish.
Heat oil in a wok or large pan for deep-frying on high heat. Add the chopped coriander root and stem, lemongrass, onion and garlic. Stir-fry 1 minute, until fragrant. Stir in paste.
Add pork and stir-fry for 1 minute. Add prawns and sugar. Stir-fry for a further minute or until the pork is nearly cooked.
Add lime leaves, tomatoes and leafy vegetables. Stir-fry 1 minute. Add noodles, fish sauce, soy sauce and chillies. Stir-fry until noodles are hot. Squeeze over lime juice.
To serve, garnish with herbs and peanuts, with lime wedges on the side.
