Cook the Asian egg noodles or spaghetti according to package directions until al dente. Drain well.
While noodles cook, prepare the dressing: In a medium bowl, whisk together chunky peanut butter, soy sauce, rice vinegar, sesame oil, honey, grated ginger, minced garlic, and sriracha until smooth. If too thick, add a splash of warm water.
Transfer the warm, drained noodles to the bowl with the dressing. Toss thoroughly to coat every noodle strand. Set aside to cool.
Thinly slice the red cabbage, carrots, radishes, cilantro, and green onions.
Once the noodles are cooled, add the sliced vegetables to the bowl. Toss everything together until well combined.
Garnish with sesame seeds and serve immediately, or chill for at least 30 minutes for best flavor.