Slice beef into half-inch strips on a separate cutting board. Rinse all vegetables. Chop green onion; mince garlic, trim snow peas, and chop bok choy into strips; set aside. In a nonstick skillet, heat oil on medium-low heat and sauté garlic for 1-2 minutes, until golden. Raise heat to medium-high, add beef and stir-fry for 1-2 minutes; add all vegetables and stir-fry another 5-6 minutes, until vegetables are tender, but still crisp.