Put the vermicelli noodles in a bowl and pour over a kettle of water. Leave until just tender, drain then rinse under cold water and drain again. To make the sauce heat the vinegar in a small pan, add the chopped chillies, sugar and garlic and stir until the sugar dissolves. Add 100ml water, the fish sauce, lime juice, carrot and ginger. Pour the dressing over the rice vermicelli, toss and leave for 2-3 minutes. Toss through the herbs, beans, pork and toss again. serve sprinkled with chopped nuts.