Trim any fat from the beef, then freeze the beef for 1 hour or just until firm enough to cut into paper-thin slices.
In a bowl, combine the soy sauce and garlic. Add the beef and toss to coat. Set aside.
Heat 2 tbls of the peanut oil in a wok over high heat. Add the asparagus spears and stir-fry for 3 minutes. then add the onions and stir-fry for a further 1 minute. Add the bean sauce and water, and stir to combine, then add the asparagus tips. Reduce the heat, cover and simmer until the asparagus is tender but not mushy
In a small bowl, combine the cornflower and 1 tablespoon cold water and stir to make a smooth paste. Push the vegetables to one side of the wok and add the cornflour paste, stirring constantly until the sauce boils and thickens. Return the beef to the wok and stir gently to combine and heat through. Server immediately with white rice.