Fill a large pot with lightly salted water and bring to a rolling boil over high heat. Once the water is boiling, stir in the Chinese noodles, and return to a boil. Cook the noodles uncovered, stirring occasionally, until they have cooked through, about 5 minutes. Drain well in a colander set in the sink. Rinse the noodles with cold water several times to chill, then drain again.
In a large salad bowl, whisk together the ketchup, sesame oil, soy sauce, brown sugar, kosher salt, and lime juice until the brown sugar has dissolved. Place the noodles, green onion, carrots, zucchini, red pepper, sesame seeds, and red pepper flakes into the bowl, and gently toss to thoroughly mix the salad and coat with dressing. Chill at least 2 hours before serving.
