Roast the beef bones in the oven or on a grill until lightly browned. Transfer to a pot, cover with water, add the onion, garlic, peppercorns, bay leaf and about a tablespoonful of salt. Cover, bring to the boil, lower the heat and simmer for about two to three hours.
After simmering for an hour and a half, turn up the heat to high, add the pork ribs and more salt. Bring to the boil once more. Watch out for scum — if scum from the pork ribs rises, scoop and throw out. Lower the heat, cover and simmer for an hour or until the pork ribs are tender to the point that the meat is falling off the bones.
Scoop out the beef leg bones, garlic, onion, peppercorns and bay leaf. Transfer the bones to a plate. Let the pork ribs continue to simmer in the broth.
When the bones are cool enough to handle, tap out the marrow. Mash the marrow lightly with a fork then pour back into the pot with the ribs.
Strip the malunggay leaves off the stems (read tips). Discard the stems; add the leaves to the soup pushing them down into the broth.
Taste the broth and add more salt, if needed.
Turn up the heat to high. When the broth boils, cover the pot and turn off the heat. Let the malunggay leaves cook in the residual heat for about five minutes.
Serve the soup at once.