Combine pork, soy sauce, ground black pepper, and garlic. Mix well. Let it stay for 15 minutes.
Heat oil in a cooking pot.
Sauté the onion until it gets soft.
Add the marinated pork including the remaining soy sauce and garlic. Cook for 5 minutes in medium heat.
Pour the beef broth in the pot. Let boil. Cook in low heat for 45 minutes or until the pork gets tender. Note: add more beef broth or water if the liquid starts to dry out.
Add the vinegar. Allow the liquid to re-boil. Stir.
Put the string beans in the pot. Cook for 3 minutes.
Add brown sugar. Stir. Continue to cook for 5 to 8 minutes.
Transfer to a serving bowl. Serve!
Share and enjoy!