Melt butter in saucepan or skillet over medium high heat and cook onion until soft. Add garlic and cook a minute longer. Put tomatoes through a food mill or puree in a blender or food processor. Add to onion mixture along with all other ingredients except meat. Bring to a boil and simmer for several minutes. Remove from heat and set aside. Thread ribs on to spit and secure with prongs. Close cover two thirds of way. Spit roast for 30 minutes, then baste every ten or so for another 40 minutes or until juices run clear. Place several tablespoons of sauce on each plate and serve with ribs. Makes about 4 servings