1. Prepare pork for cooking by trimming off fat cap and silver skin. Cut pork into 8 similar-sized pieces. Rub barbecue seasoning on each piece. In 2-cup measuring cup, combine broth, vinegar, brown sugar, tomato paste, chipotle liquid, mustard, soy sauce and Worcestershire sauce. Stir to combine; set aside.
2. Heat a 6-quart or larger pressure cooker using the SAUTE or BROWN setting. When ready, add oil. Working in batches, begin browning pork pieces on all sides. Brown for 3 to 4 minutes per side. When all sides are brown, remove and set aside. After browning meat, turn off pressure cooker. 
3. Place all meat in cooking vessel. Add garlic and onions; pour in the sauce mixture. Make sure pot is not filled more than 2/3 full. Secure lid of pressure cooker into locked position. Turn regulator knob to PRESSURE. Turn on pressure cooker, and set to PRESSURE COOK on HIGH for 40 minutes. After time has elapsed, turn off pressure cooker. Allow pressure to release naturally without turning pressure regulator knob. (This will give the meat time to absorb juices and liquid in cooker. It should take about 20 minutes for pressure to release. The floating valve will drop, and you will be able to open the lid.)
4. Unlock lid. Tilt to open away from you to avoid any remaining steam in the pot. Remove pork from pressure cooker; place in large bowl. Use a slotted spoon to ladle out onions and garlic; add them to pork. Using two forks, shred the pork. Pour remaining liquid into a saucepan. Bring to a boil; let boil for 10 minutes. Pour 3/4 cup sauce over pork. Serve on a baked potato, tortillas or a sandwich. Serve remaining sauce on the side.

Calories: 506, Fat: 32 g (11 g Saturated Fat), Cholesterol: 141 mg, Sodium: 438 mg, Carbohydrates: 11 g, Fiber: 1 g, Protein: 41 g.