In a skillet, heat oil over medium heat. Add onions; cook until soft. Add garlic, chili powder and peppercorns; cook, stirring, for 1 minute. Add brown sugar, vinegar, Worcestershire sauce and liquid smoke. Stir to combine; bring to a boil. Place pork in crockpot, pour sauce over pork. Cover and cook on low for 10-12 hours or on high for 6 hours, until pork is falling apart.
Transfer pork to a cutting board; pull the meat apart in shreds, using two forks. Return to sauce and keep warm. When ready to serve, spoon shredded pork and sauce over warm buns.
Note: You can prepare sauce in advance and refrigerate overnight. The next morning, proceed as directed.
Yield: 6-8 servings