Spray 4-quart slow cooker with cooking spray. Place onion in slow cooker.
In 12-inch skillet, heat oil over medium-high heat. Cook pork in oil until brown on all sides. Place pork over onion in slow cooker. Sprinkle with cumin, salt, garlic powder and chili powder. Pour broth around pork.
Cover; cook on Low heat setting 8 to 10 hours.
Remove pork from slow cooker to plate; shred pork, using 2 forks. Place in serving bowl. Using slotted spoon, remove onion from slow cooker and add to bowl with pork. If desired, toss pork mixture with small amount of cooking liquid. Discard remaining cooking liquid.