1finely chopped chipotle chile pepper in adobo sauce
Trim excess fat from boneless, skinless chicken thighs and place on a foil-lined baking sheet.
In a small bowl, combine all spice rub ingredients - smoked paprika, brown sugar, salt, dry mustard,garlic powder, chili powder, cumin and black pepper. Sprinkle and pat mixture evenly on both sides of chicken thighs. Cover the baking sheet with foil and chill for 30 minutes.
Meanwhile, in a small saucepan, combine the bbq sauce ingredients - ketchup, maple syrup, molasses, finely chopped chipotle pepper, Worcestershire sauce, Dijon mustard, and garlic powder (reserve lime juice for later). Bring just to boiling; reduce heat to low, and simmer uncovered for 15 minutes, stirring occasionally. Set aside.
Prepare a gas or charcoal grill for direct cooking over medium heat. Arrange chicken on a lightly oiled grill rack, cover grill, and cook 4 minutes. Flip and cook 3 to 4 minutes more.
Stir lime juice into the sauce and baste the chicken with some of the sauce, flip and cook 1 minute. Brush sauce on the second side and cook until done (170 degrees F.). Remove chicken from the grill and let it rest 5 minutes. Serve with lime wedges on the side, if desired.
If desired, The Chipotle Maple BBQ Sauce can be prepared in advance, transferred to an airtight container, and refrigerated until ready to use.