Prepare the Spicy Peanut Sauce first. This can be made up to a few days in advance. Blend all peanut sauce ingredients in a blender or food processor until smooth. Set aside if using right away, or refrigerate (or freeze) if making it in advance.
Bring a large pot of lightly salted water to a boil. Add rice noodles to water and let stand for 8 - 10 minutes (or follow package directions, depending on the type of noodles you're using), stirring after 2 minutes to break up noodles. Remove from heat, drain and rinse thoroughly with cold water. Set aside.
Prepare all vegetables and transfer to a large bowl with the cooled, rinsed and drained noodles.
Just before serving, toss with the peanut sauce and garnish with cilantro, peanuts, and optional sesame seeds.