Heat 2 teaspoons of vegetable oil over medium high heat in a large pan. Add the carrots and white onions to the pan.
Cook for 3-5 minutes or until vegetables are softened.
Add the green onions and garlic and cook for 30 seconds. Remove the vegetables from the pan, and cover to keep warm.
Rinse the noodles under hot water to separate them.
Heat the remaining tablespoon of vegetable oil in the pan. Add the noodles and cook for 3-4 minutes per side or until browned and crispy on the edges.
Add the vegetables back to the pan.
In a small bowl, whisk together the soy sauce, hoisin sauce, sesame oil, cornstarch and 2 tablespoons of cold water.
Add the bean sprouts to the pan, and toss to combine.
Add the sauce to the pan and bring to a simmer. Cook for 2-3 minutes or until sauce has just thickened and bean sprouts have wilted.
Sprinkle with sesame seeds and additional green onions if desired, then serve.