Bring a large pot of salted water to a boil and cook the linguini according to the package directions. Drain and rinse with cold water.
Heat the oil in a large skillet or wok over medium-high heat, add the onions and mushrooms and cook, stirring occasionally until soft and browned, about 10 minutes. Add the cabbage and carrots and cook, stirring for 2 minutes. Add the Mongolian Sauce, drained pasta, red pepper flakes, and cook, stirring, for 1 - 2 minutes or until heated through. Garnish with the green onions.