Mix first 10 ingredients in large resealable plastic bag. Add pork to marinade. Close bag and turn pork to coat. Refrigerate overnight, turning pork once.
Preheat oven to 400. Transfer pork to baking pan; discard marinade. Roast until thermometer inserted into center of pork registers 150 F, about 25 minutes. Let pork stand 5 minutes. Cut pork crosswise into 1/2-inch-thick slices. Arrange on platter. Garnish with orange slices and cilantro sprigs and serve.