1. In a zip-top bag or a large container with a lid, combine the pork, onions and 1 cup mojo. Seal bag and transfer to refrigerator; chill at least 3 hours, or overnight.
2. Prepare a grill to medium-high heat, or heat a large, lightly-greased grill pan over medium-high heat. Remove pork and onions from the marinade; discard any leftover liquid. Season pork with adobo. Cook pork until golden brown and internal temperature registers 160°F on a quick-read thermometer, basting with remaining mojo, flipping once, 15 - 20 minutes. Cook onions until soft and golden brown, about 10 minutes.
3. Divide pork and onions evenly among serving dishes.
* If you do not have a self-sealing bag, be sure to use a non-reactive container such as a glass or stainless steel baking dish to marinate your chops. Do not use aluminum.