Put oven rack in middle position and preheat oven to 325°F.
Sprinkle ribs evenly with salt.
Bring orange juice, soy sauce, sugar, ginger, garlic, and pepper to a boil in roasting pan over moderately high heat, stirring until sugar is dissolved. Add ribs in 1 layer using tongs, turning to coat, and cover pan tightly with foil.
Braise ribs in oven until very tender, about 2 hours. (If making ahead, see cooks' note, below.)
Before serving:
Reduce oven temperature to 200°F.
Transfer ribs to a baking dish, arranging them in 1 layer, and keep warm in oven.
Skim fat from cooking liquid if desired, then make glaze by boiling liquid, uncovered, stirring occasionally, until syrupy and reduced to about 3/4 cup, about 15 minutes. Brush glaze generously on ribs.