1Rinse the 800g beef ribs under cold water to remove any bone fragments and excess blood. Pat dry with paper towels.
Slice the medium onion into thin wedges and set aside.
In a large pot or Dutch oven, combine 2 cups water, 3 tablespoons soy sauce, 2 tablespoons brown sugar, 2 teaspoons grated garlic, 1 tablespoon sesame seed oil, and 1 teaspoon black pepper. Stir well to mix.
Add the beef ribs and sliced onion to the pot, ensuring the ribs are mostly submerged in the liquid.
Bring the mixture to a boil over medium-high heat. Once boiling, reduce the heat to low, cover, and simmer for
5 to 2 hours, or until the beef is tender and the sauce has thickened slightly.
Occasionally skim off any foam or impurities that rise to the surface during cooking.
Once the ribs are tender, taste and adjust seasoning if needed. Serve hot, garnished with sliced green onions or sesame seeds if desired.