Step 1 Use 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 2 Add 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.