Preheat the oven to medium heat.
Cut each full rack ribs into 2, so you have 4 halves.
Sprinkle salt, pepper and chili powder over the meat. Wrap it with aluminum foil and bake for about 2 hours.
In a medium saucepan over medium heat, heat oil.
Cook and stir the onions in oil for 5 minutes. Stir in water, tomato paste, vinegar, brown sugar, honey, and Worcestershire sauce.
Season with salt, black pepper, liquid smoke,, garlic powder, paprika, onion powder, dark molasses, and chili powder.
Simmer the mixture until sauce thickens. Remove from heat, and set sauce aside.
Preheat outdoor grill to medium heat.
Remove the ribs from the oven, and let stand 10 minutes. Remove the racks from the foil, and place on the grill.
Grill the ribs for 3 to 4 minutes on each side. Brush sauce on the ribs while they are on the grill. Serve.