Cook cellophane noodles according to the package instructions. Rinse under cold water, drain, cut noodles 2-3 times with a pair of scissors, then squeeze out all excess liquid by hand. → This last step helps prevent your salad from being too watery, which would result in a diluted and less intense dressing.
Roughly chop the cilantro and set the stems aside for the dressing.
Place cooked cellophane noodles, cherry tomatoes, scallion, carrot, celery, peanuts, and chopped cilantro leaves in a large bowl.
Dressing: Place cilantro stems, garlic, ginger, and Thai chilies in a mortar and pound into a paste. Add sugar and salt, pound until dissolved. Add lime juice and soy sauce, stir to mix. → If you don't have a mortar, finely mince cilantro stems, garlic, ginger, and Thai chilies, then place them with the sugar, salt, lime juice, and soy sauce in a bowl and stir to mix.
Drizzle the dressing over the salad and toss to combine.
Notes
Use Chinese celery if you have the chance to (only available in large Asian Shops). Otherwise, the inner stalks and leaves of celery will do fine.
Leftovers can be stored in an airtight container in the refrigerator for up to 2 days.