Stir together first 5 ingredients until mixture is smooth.
Heat 1 1/2 tablespoons vegetable oil in a large skillet or wok over medium-high heat 2 minutes. Add beef, in batches, and stir-fry 8 minutes or until no longer pink. Remove from skillet; set aside.
Pour remaining 1 1/2 tablespoons vegetable oil in skillet; heat 2 minutes. Add green onions, and stir-fry 5 minutes or until tender.
Return beef to skillet; stir-fry 2 minutes or until heated. Serve immediately over hot cooked rice.