Preheat oven to 450. Season ribs with salt and pepper. Put, meaty side down, in shallow roasting pan and roast at 450 for 30 minutes. Remove ribs from oven, drain excess fat from pan, and turn meaty side up. Lower oven temperature to 350 and continue roasting for 30 minutes. Reduce heat to 300 and roast another j30 minutes. During the last 30 minutes of roasting, spread barbecue sauce over both sides of ribs, turning and basting til ribs are tender and glazed.
For the barbecue sauce, while ribs are roasting, in medium pan, mix tomato paste, ketchup, water, white vinegar, lemon juice, brown sugar, Worcestershire sauce, allspice, garlic, onion, and salt and simmer over low heat for about 30 minutes.
Back ribs come from the back or loin of the pig and are often called loin back ribs. They have more meat than spareribs and are not as fatty. Baby back ribs are a narrower slab of back ribs and are sometimes called riblets. Plan to buy 1 lb. of baby back ribs per person.