1/2 cup prepared molasses or other sweet barbeque sauce
2 Tbsp. reserved pineapple juice
1 chipotle pepper in adobo sauce, seeded and minced
Drain pineapple, reserving 1/4 cup juice for marinade and barbeque sauce. Cover and refrigerate pineapple rings until ready to use.
Whisk marinade ingredients in small bowl. Season steaks with black pepper. Place in food-safe plastic bag. Pour marinade over steaks; turn steaks to coat. Close bags securely and marinate in refrigerator 15 minutes to 2 hours.
Meanwhile combine barbeque sauce ingredients in small bowl. Set aside.
Remove steaks from marinade; discard marinade. Place steaks on grill over medium, ash-covered coals. Grill Flat Iron Steaks, covered, 10 to 14 minutes for medium rare to medium doneness, turning once. About 8 minutes before steaks are done, place pineapple rings on grill. Grill until heated through, turning once.
Season steaks with salt, as desired. Drizzle steaks and pineapple with sweet & smoky barbeque sauce.
Garnish with lime slices and cilantro sprigs, if desired.