1. Preheat grill for medium heat and lightly oil grate.
2. Heat oil in a saucepan over medium heat. Saute minced onion for about 5 minutes, or until caramelized. Stir in honey, mustard, and vinegar. Season with crushed red pepper, Cajun seasoning, salt, and black pepper. Reduce heat, and simmer 5 minutes, stirring occasionally. Remove from heat, and set aside.
3. Trim the membrane sheath from the back of each rack. Run a small, sharp knife between the membrane and each rib, and snip off the membrane as much as possible. Generously sprinkle ribs with salt and pepper on both sides. Place ribs on grill rack, cover, and open vents halfway. Cook for 50 minutes. Turn ribs once, making sure they are not being over-cooked. Brush tops of ribs with sauce, and cook covered for 5 to 10 minutes Turn ribs over, cover, and cook for another 5 to 10 minutes. Remove ribs from grill. Heat remaining sauce, and serve as a dipping or mopping sauce.
** This recipe works well on Baby Back Ribs as well. Just subtract 15 minutes from cook time**