Bring a large pot of salted water to a boil.
In a small bowl, whisk together soy sauce, rice vinegar, sugar, and sesame oil.
In a large skillet over medium heat, warm the oil. Add the sesame seeds and red pepper flakes. Cook until the pepper flakes become fragrant and the seeds start to brown, about 3 to 5 minutes. Take the skillet off the heat and stir in the scallions and the soy sauce mixture.
Place the sliced vegetables in a colander in the sink.
Cook the noodles until al dente by following the package instructions. Once the noodles are done cooking, drain them over the vegetables in the colander.
Heat the sauce in the skillet up to a simmer. Add the noodles and vegetables back to the skillet and stir well to combine.