Put oven rack in lower third of oven and preheat oven to 350°F. Line a 17- by 12- by 1-inch shallow baking pan with foil.
Stir together all sauce ingredients in a 2-quart heavy saucepan and bring to a boil over moderate heat. Reduce heat and simmer, covered, 15 minutes.
Transfer sauce to a food processor and purée until smooth.
Coat both sides of ribs with sauce. Arrange ribs, meaty side up, in 1 layer in baking pan, overlapping if necessary. Cover pan tightly with foil and bake ribs 1 hour. Remove foil (from top) and bake ribs 1 hour more.