1. Heat oven to 200 degree F. In a medium saucepan, heat oil over medium heat. Add onion and cook 5 to 7 minutes, stirring occasionally until translucent . Stir in garlic and cook 1 minute more. Stir in water, vinegar, molasses, Worcestershire sauce, mustard, chili powder, salt, pepper, ginger, and tomato paste and cook over low heat 5 minutes, stirring frequently until mixture begins to thicken.
2. Place ribs in a 9x13-inch glass baking dish (you may need to cut the rack end off to make it fit in the pan. If so, simply fit the cut piece into the pan, keeping as even a layer as possible.) Pour sauce over ribs. Cover dish tightly with heavy duty aluminum foil, and bake until ribs are tender, about 4 hours.
3. Heat grill. Carefully transfer ribs to a platter, letting most of the sauce drip off. Transfer sauce to a small saucepan. Place pan with sauce on corner of the grill to heat. Grill ribs uncovered, 10 to 15 minutes, turning occasionally. During the last 5 minutes of grilling, brush both sides of the ribs with the sauce. Transfer ribs to a serving platter and serve remaining sauce in a bowl on the side. Makes 4 to 6 servings.