Prep: In large bowl, combine water, beer, salt, sugar, molasses, 1 tablespoon garlic and mustard seeds; stir to dissolve sugar and salt.
Combine: Stir in onions and rosemary sprigs; add pork chops, covering with brine. Cover; refrigerate a minimum of 4 hours or up to 24 hours; turning occasionally.
In small bowl, combine olive oil, black pepper, remaining 1tablespoon garlic and 1 tablespoon chopped rosemary; set aside. Remove pork chops from brine; discard brine. Lightly rinse porkchops; pat dry. Brush pork chops with olive oil mixture; set aside.
Create: Prepare grill to medium heat. Place pork chops on grill; grill, turning occasionally, until internal temperature reaches 155°F on an instant read thermometer (about 20-40 minutes depending on thickness). Remove from grill and let rest 5 minutes before serving.