Place ribs, meaty side down, in shallow roasting pan.
Roast at 450° for 30 minutes.
Remove meat from oven; drain off excess fat.
Turn ribs meaty side up; season with the salt.
Reduce oven temperature to 350° and continue roasting for 1 hour; drain.
Meanwhile, prepare plum glaze by combining preserves, orange juice concentrate, vinegar, and Worcestershire sauce; blend.
Pour glaze over ribs; roast 30 minutes or till lender, basting occasionally.