Prepare Chashu Pork, substituting 2 to 4 pounds duck legs for the pork belly. Cook until tender, 3 to 4 hours. Remove the duck legs from the sauce, discard the green onions, and reduce the sauce until slightly thickened and syrupy. Prepare a hot grill fire. Brush the duck legs with the reduced sauce, place on the grill, and cook briefly just until charred on all sides, about 5 minutes total. Serve with cooked jasmine rice.