In large resealable container or bowl, combine pork shoulder, marinade and garlic; cover and refrigerate for at least 2 hours or up to overnight.
Preheat oven to 425ºF. Remove pork shoulder from marinade; season all over with Adobo seasoning. Place fat side up in roasting pan fitted with rack.
Cook in lower third of oven for 30 minutes. Reduce temperature to 325°F. Roast for 2 to 2 1/2 hours or until thermometer inserted in center registers 160°F.
Tent loosely with foil; let stand for 20 minutes. Slice and serve with drizzle of pan juices Garnish platter with orange slices and cilantro if desired.
Note: Use leftover pork shoulder for sandwiches, pastas or soups.