Asparagus and beef with black beans

1 tb Salted preserved black beans
      2    garlic cloves; minced
      2 sl Ginger (quarter-sized)
           - minced
    1/2 lb flank steak
      1 sm Onion; sliced
      1 lb Asparagus; cut into 1/2-in
           -  thick diagonal pieces
      3 tb Peanut oil
    1/2 ts Salt
      1 tb Dark soy sauce
    1/2 c  chicken stock
      2 ts Cornstarch; mixed with
      1 tb Water
    1/2 ts Sugar
    1/2 tb Oyster sauce
      1 ds Sesame oil
           Hot steamed rice

-------------------------------BEEF MARINADE-------------------------------
    1/2 ts Sugar
      1 tb Rice wine or dry sherry
    1/2 tb soy sauce
      1 ts Cornstarch
    1/2 ts Sesame oil
 
  COVER THE BLACK BEANS with warm water for 5 minutes. Drain. Rinse
  thoroughly to remove salt. Put into a bowl with the garlic and ginger; mash
  into a paste and set aside. Slice the beef against the grain into 1/4-inch
  thick slices; toss with the beef marinade. Set aside for 10 minutes.
  Preheat a wok until hot. Add 2 tablespoons of the oil. Over high heat, add
  beef and stir-fry for a minute or until seared; remove and set aside. While
  wok is hot, add remaining oil, salt and reserved black-bean paste; stir-fry
  until fragrant, a few seconds. Toss in the onions, stir-fry for 10 seconds,
  then add the asparagus in 2-or-3 batches, seconds apart, making certain the
  wok is hot before adding the next batch. Toss and stir until asparagus are
  coated with the oil. Sprinkle with soy sauce, toss together, then pour in
  the stock and bring to a boil. If the asparagus needs more cooking, cover
  for a minute. Meanwhile, stir the cornstarch, water, sugar and oyster sauce
  into a smooth paste. When the asparagus is tender but still crisp, add the
  cornstarch liquid into the center of the wok. Immediately stir until
  thickened, about 10 seconds. Return the beef, add a desh of sesame oil;
  toss to mix. Serve hot over rice.