Step 1Use a cleaver or heavy knife to chop the neck, wing joints and feet at 1-inch intervals. Transfer to a large pot. Add the broth, water, ginger and green onion. Bring to a boil over high heat and simmer, partially covered, for 15 minutes.
Step 2Add the duck carcass to the broth (break or cut it up as needed so that it will fit into the pot; it may not be completely submerged) and return the broth to a boil. Partially cover and reduce the heat to a simmer. Continue to cook for 30 to 40 minutes, then remove from heat.
Step 3Position a mesh strainer over a clean pot. Strain the broth into the pot and discard the solids. Bring the broth to a boil, add the cabbage and cook for about 3 minutes, until soft and cooked through. Taste and add extra salt, if needed.
Step 4Transfer to a bowl, sprinkle on some Sichuan peppercorn for depth and garnish with the cilantro. Serve immediately.