Seolleongtang (Ox Bone Soup)

Rinse the beef bones thoroughly under cold running water to remove any surface impurities.

Place the rinsed bones in a large pot and cover with cold water. Let them soak for at least 4-6 hours, or preferably overnight in the refrigerator, changing the water every 2-3 hours to draw out blood and impurities.

Drain the soaked bones and place them back into the clean large pot. Add enough fresh cold water to cover the bones completely, then bring to a rolling boil over high heat for 10-15 minutes. This blanching step removes further impurities and scum.