Bring a large pot of water to a boil.
Cook noodles according to package instructions and then drain, but save a couple of cups of the noodle water (don't forget to do this!).
Blend all ingredients except noodles, scallions, and sesame seeds in a food processor or blender until smooth. Set aside.
Add the noodles to a large bowl and then toss with the sauce.
Serve hot or at room temperature.
Garnish with scallions, sesame seeds, and extra chili oil (if desired).
