Originally from the Silver Spoon Cookbook- Kosher cooking for the discerning palate. Original recipe in the book calls for a 1 1/2 lb corned beef, however the sauce is enough for a 3 lb. corned beef.
2½-3 lb corned beef
½ cup mustard
⅔ cup brown sugar
1 (11 oz) mandarin oranges- with juice
Place corned beef in a large pot with water to cover. Cook for 3 hours or until tender.
Cool and slice. Place slices in a baking pan.
Combine sauce ingredients and mix well. Pour sauce over corned beef, cover pan tightly and bake at 350F for 30 minutes.