Heat oil in a large pan. Add pork and cook until browned on all sides.
Place onion slices in bottom of crock pot.
Transfer pork to crock pot and sprinkle with jerk seasoning, salt, and pepper. Squeeze orange slices onto pork and drop orange slices into crock pot. Pour beef broth around sides of pork.
Cover crock pot and cook on HIGH for 6 hours or LOW for 8 hours.
Discard cooking liquid and using 2 forks, shred pork and place in a bowl.
To make slaw, place cabbage and shredded carrots in a medium bowl. Add mayonnaise, cilantro, lime juice, sugar, salt, and jalapeno and toss.
To serve, place about 1/2 cup pork on each tortilla and top with slaw, mango and bbq sauce.