In a large pot, bring the meat, onion, scallions, garlic, ginger and peppercorns to a boil, uncovered, in 14 cups of water. Reduce the heat to medium to medium low to keep it at medium boil, and skim off the scum. Continue to boil, covered, until the meat is tender, about 1 hour. Stir in soup soy sauce with 10 minutes remaining. Remove the meat and cool. Discard the vegetables. Cool the broth.