Combine the pork shoulder, soy sauce, garlic, bay leaves, sugar, oyster sauce, and whole peppercorn in a bowl. Mix well. Let it stay for at least 30 minutes so that the pork can absorb the flavors.
Transfer the content of the bowl to a slow cooker or crock pot. Pour-in the beef broth. Set the level to high, cover, and slow cook for 5 hours.
Add the vinegar and salt. Continue to slow cook for 30 minutes to 1 hour.
Add the boiled eggs. Transfer to a serving bowl.
Serve. Share and enjoy!