Place the onions in the bottom of a 5-quart slow cooker. Place the pork shoulder, fat and skin side up. in the slow cooker. In a medium bowl stir together soy sauce, garlic, salt pepper and orange marmalade. Pour mixture over the pork. Cover and cook on low for 8 hours.
Remove shoulder to a serving platter and let rest for 5 minutes. Break up some of the meat with a fork and arrange on platter. Leave the rest of the meat on the bone to keep it warm and moist and let your guest pull it off the as they need it.
Wrap the tortillas in damp towels, 10 to a towel and microwave on high for 30 seconds. Set out pork and tortillas with Cabbage Slaw and have guests assemble their own tacos.
Combine shredded cabbage and grated carrots in a large bowl. Add vinegar, salt, and pepper and toss to combine. Cover with a damp towel and let sit in refrigerator for at least 1 hour or up to 8 hours. Use as topping for pulled pork tacos.
Use the leftovers from this recipe to make Pulled Pork Sliders with Mustard BBQ Sauce and Pickled Onions.