Wash the bones under running water. Clean the pot. Return the bones back to the pot. Add water, the onion, garlic, ginger and scallion. Bring it to a boil.
Blanch the cabbage until the white parts turn soft. Remove the cabbage from the pot and shock in cold water to stop the cooking. Drain and squeeze out water.
Remove the meat from the broth. Discard the aromatic vegetables, reserving the broth. Place the bone back. Add the cabbage, potatoes, and the remaining seasoning. Boil.