Rinse and pat dry duck then rub baking soda into the skin. Sprinkle inside and out with salt. Rinse any giblets in water and pat dry. Set aside.
In a saucepan over medium heat, melt butter and sauté chopped onions until lightly browned.
Drain sauerkraut; reserving the liquid. In a bowl add the sauerkraut, diced apples, diced celery, and caraway seed to the onion mixture; mix well. Fill the cavity of the duck and truss. Place any remaining stuffing in the roasting pan around the duck. Bury the giblets in the dressing. Cover and bake in a 350° F oven for 3 hours.
Uncover the last hour of cooking to brown the duck. Baste with the sauerkraut liquid.Servings: 6