Heat grill to medium. In small bowl, combine brown sugar, paprika, cumin, salt and ground chile. Rub mixture over pork tenderloins, pressing onto pork. Any mixture that falls off, scoop up and reapply.
In separate bowl, stir together molasses, lemon juice and garlic.
Place pork on grill over medium heat 4-6 inches from heat. Grill until browned on each side, turning to brown all sides. When browned, baste with molasses mop sauce. Continue grilling, basting frequently for 10-15 minutes, until internal temperature reaches 160°.
Remove from grill and cover loosely with foil. Let pork rest at least 10 minutes before slicing.
Tip & Tidbits
To prevent the sugar in the rub and mop from burning, turn and baste pork frequently.