Measure and cut all the ingredients for the recipe. In a bowl, mix together all the sauce ingredients. Bring a pot of water to a boil and cook the noodles until al dente.

While the noodles are cooking, toss the shrimp with the cornstarch. Heat a wok or skillet with the oil, sear the shrimp on both sides, then set aside. Using the same wok, stir-fry the garlic and onion.

Add and stir-fry the bell peppers and mushrooms together. Add the napa cabbage, shrimp, half of the sauce, and stir-fry for 1 minute. Drain the noodles, add them to the wok with the rest of the sauce, and toss to combine.

Serve immediately and sprinkle with chopped cilantro for garnish.