Cook pasta to al dente, with a bite to it, then cold shock it to stop the cooking process by running it under cold water in colander. Drain the pasta very well.
In the bottom of a large bowl, whisk together soy, peanut butter, vinegar, oil, sesame oil, and hot sauce. Add noodles and veggies and toss to combine the noodles and coat them evenly with sauce. Sprinkle scallions and sesame seeds throughout the salad and serve.