Dry mung bean noodles are very light. Soak the dry mung bean noodles in warm water for about 10 minutes, or until soft. Discard the water, drain thoroughly, and set aside (use 4 oz (125 g) for this recipe).
Boil some water and add the noodles, cooking according to the package instructions (usually a couple of minutes or until just cooked through but not mushy). Remove the noodles and drain. In the same water, boil the shrimp until completely cooked, then remove and set aside.
Mix all the ingredients for the dressing well, ensuring that the sugar is completely dissolved. Set aside.
In a salad bowl, combine the mung bean noodles, shrimp, shallots, tomato, cilantro, and mint with the dressing. Toss to blend well. Add the roasted cashew nuts and stir to combine. Serve immediately at room temperature, or chill in the refrigerator for 30 minutes before serving.