This recipe was tested on a 4.5 pound pork butt. But if you're cooking with a smaller pork butt ( about 3.5 pounds) and don't like too much sauce, then make half the sauce. If you're making the full batch of sauce on a smaller pork butt, you'll have plenty of sauce left over for your sliders, tacos, pasta, noodles or rice. Cooking the pork longer will make the sauce caramelize and becomes dark, charred and sticky sweet brown sauce. Cook the pulled pork for a little longer to make the pork more tender and melt-in-your-mouth. We prefer to use a bone-in pork shoulder, but it works great with a de-boned pork too.
Add oil evenly to outside of pork shoulder and season all sides with salt and pepper. Heat large cast iron pan or deep oven proof skillet on medium-high heat. Sear each side of the pork shoulder on the hot pan until the pork is brown. About 3 minutes per side. Remove the pork from the skillet and set aside.
In the same oven proof skillet, heat to medium heat. Add oil, onion and garlic. Cook onions and garlic until soft and fragrant. Add tomatoes, ginger, fish sauce, chili garlic sauce, mustard, brown sugar and black pepper. Stir together until well combined. Add the seared pork back into the skillet.
Coat the seared pork with the sauce, ladling the tomato sauce mixture over to coat completely. Cover the pork with aluminum foil.
Bake the pork for about 4 hours, or until the pork is tender and easily shreds with a fork. Skim off any excess fat, then shred the pork in the sauce.
Keep foil over the shredded pork to keep it warm before serving. It tastes even better the next day! Serve on tacos, sliders, sandwiches, pasta or on rice. Don't waste the yummy sauce!