Combine Rub ingredients in a spice grinder. Pulse on and off until grind has sand-like consistency. Set aside.
Preheat large cast iron skillet on medium-high heat for 5 minutes. Add pancetta; cook 7 to 10 minutes until crisp, stirring occasionally. Using a slotted spoon, remove pancetta; set aside. Pour excess oil from pan. Return same skillet to heat; add onion and garlic. Reduce heat to medium; cook 3 to 5 minutes until onions are translucent, stirring often. Stir in pancetta, beans, tomatoes, poblanos, broth, jalapeno, chili powder, cumin and coriander. Reduce heat to low; simmer 15 to 20 minutes, stirring occasionally. Add chocolate during last 5 minutes of cooking; stir until combined.
Meanwhile, press Rub evenly on steaks. Place steaks on grid over medium, ash-covered coals. Grill, covered, 11 to 16 minutes (over medium heat on preheated gas grill, 15 to 19 minutes) for medium rare (145°F) to medium (160°F) doneness, turning occasionally. Remove bones and carve steaks into slices. Serve with Charro Beans.
Nutrition information per serving: 452 Calories; 219.6 kcal Calories from fat; 24.4 g Total Fat; 11.4 g Saturated Fat; 0 g Trans Fat; 0.4 g Polyunsaturated Fat; 3.6 g Monounsaturated Fat; 68 mg Cholesterol; 904 mg Sodium; 24 g Total Carbohydrate; 1.7 g Dietary Fiber; 34 g Protein; 6 mg Iron; 522 mg Potassium; 4.4 mg Niacin; 0.4 mg Vitamin B6; 1.9 mcg Vitamin B12; 5 mg Zinc; 9.1 mcg Selenium; 87.1 mg Choline;