Roast duckling a la orange

4    5-pound ducklings
      1 ts Seasoned salt
    1/2 ts Rosemary
    1/2 c  Celery; chopped
    1/2 c  Onion; chopped
      2 c  Brown sauce; or chicken stoc
      3 tb Sugar
      1 tb butter
    1/2 c  Vinegar
      1 c  Orange juice
      1 ts English mustard
    1/2 ts Cornstarch
    1/4 c  Grand marnier
 
  Recipe by: Joe Mannke of Rotisserie for Beef and Bird, Houston, TX
  Preparation Time: 2:00
  STEP ONE: Prepare the Duckling and Basic Brown Sauce--
  Trim the duck of excess fat at the base of the tail. Rub the inside with
  the seasoning salt and rosemary.
  
  Preheat oven to 450 degrees F.
  
  Place the duckling in a roasting pan, add 1/2 cup of water, and roast for
  1-1/2 hours, basting occasionally.
  
  Remove the duckling from the oven and keep warm.
  
  Pour off all but two tablespoons of fat from the roasting pan, add the
  onions and celery, and saute until tender. Add two cups of brown sauce.
  Boil for 20 minutes.
  
  The  basic sauce is now ready for additional flavoring.
  
  STEP TWO: Prepare the Orange Sauce-- Melt the butter, vinegar, and sugar
  in a saucepan and boil until the liquid caramelizes. Add the orange
  juice, mustard, and basic brown sauce and bring to a boil.
  
  Strain the sauce, then thicken with cornstarch and season with Grand
  Marnier.