While noodles are cooking, heat oil in a wok or a 12-inch deep saute pan set over medium-high heat. Add chicken and saute until cooked through, about 6 minutes. If using shrimp cook about 1 1/2 minutes per side or until opaque.
Transfer to a plate, leaving oil in pan. Add bell pepper and carrots saute 1 - 2 minutes then add garlic, green onions and bean sprouts saute 1 minute longer.