Preheat oven to 300°F. Mix dry rub ingredients and rub generously on both sides of rack of ribs. Let stand for 1 hour min.
Melt butter and saute onions, garlic and peppers until just translucent. In large sauce pan, mix sauteed items in with broths, add vinegar, sugar, Worcestershire sauce, mustard, hot sauce, squeezed lemon juice and pulp, cayenne pepper, ketchup and fresh ground salt and pepper. Mix well. Heat on high heat to boil then reduce heat to simmer. Simmer, uncovered until sauce begins to thicken, approx. 1 hour.
Place rack of ribs in oven, turning every 45 minutes and brushing sauce on each side. Slow roast approx 3-4 hours or until meat begins to fall away from bone. Add last coating of sauce just before removing from oven, then let stand approx. 15 min before serving.