In a large pot, combine 12 cups water, the cilantro, shallot, garlic, lemongrass, scallions, black pepper, white pepper, turmeric, salt and chicken.
Bring to a boil over high, then reduce heat to medium-low and simmer until the chicken is tender, about 30 minutes.
Remove from the heat and stir in the fish sauce and sugar.
You can remove the chicken and pull it off the bone into shreds, stirring it back into the broth, or serve it bone in.
Serve hot on its own or with glass noodles or rice, topped with cilantro, fried shallots, chiles, scallions and lime wedges.
