1Heat sesame oil and olive oil in a large wok or frying pan over medium heat; cook and stir shrimp and onion in the hot oil until coated. Mix mushrooms, green bell pepper, and garlic into shrimp mixture, stirring constantly. Add ginger and stir.
2Pour water and oyster sauce into shrimp mixture; simmer until shrimp are bright pink on the outside and the meat is no longer transparent in the center, 5 minutes. Stir well.
3Mix noodles and bean sprouts into shrimp mixture; toss to combine. Cook until noodles are heated through, 2 minutes. Toss again.