Heat oil in a pan over medium-high heat then sear each side of the pork shoulder for about 3 minutes per side
In a crock pot, place the seared pork shoulder and onion then pour in soy sauce, hoisin sauce, garlic, ginger, star anise, cinnamon sticks, black pepper, sesame oil, rice vinegar and honey. Stir well.
Cook on high for about 4 hours or low heat for 8 hours