In a large pot of boiling salted water, cook the spaghetti or noodles according to package instructions until al dente. Drain and rinse under cold water to stop cooking. Set aside.
In a small bowl, whisk together the toasted sesame oil, soy sauce, rice vinegar, honey or agave syrup, and sriracha until well combined.
In a large mixing bowl, toss the cooled noodles with the prepared sauce, ensuring the noodles are evenly coated.
Gently fold in the julienned carrots, sliced bell pepper, and half of the green onions into the noodle mixture.
Transfer the noodles to a serving dish or individual bowls. Sprinkle with sesame seeds, the remaining green onions, and fresh cilantro on top for a pop of color and flavor.