Puree cilantro, 2 tbsp fish/soy sauce, lemongrass bulb, garlic, lime zest, lime juice and ground pepper in blender to a course paste.
Coat chicken with mixture and refrigerate for at least 30 minutes. Turn chicken (recoating with excess in dish) 15 minutes after refrigerating.
Place scallions, peppers, jicama and snow peas in large mixing bowl. Whisk sugar, 1 tbsp fish/soy sauce, chili sauce, sesame oil and sesame seeds in small mixing bowl. Pour sauce mixture onto vegetables and mix thoroughly. Cover and refrigerate until ready to serve (can be made 24 hrs ahead).
Remove chicken from refrigerator and prepare grill medium to high heat.
Boil water for rice noodles.
Grill chicken (with marinade paste on) until cooked thoroughly. Remove from heat, cover and let rest.
Add noodles to boiling water and turn off heat. Let soak until tender and drain (adding a dash of extra-virgin olive oil to prevent sticking).
Plate noodles and top with slaw. Add chicken on top of noodles and slaw and garnish with cilantro.