Chinese greens, mustardy and sweet, add a fresh crunch to this rich, aromatic soup. The flavors are light, but this soup is hearty enough to serve as a one-bowl meal.
To make the stock: Put the chicken, onion, ginger, and chile in a large stockpot with 12 cups water. Bring the mixture to a steady gentle simmer over medium heat and cook until the chicken is cooked through and tender, about 45 minutes. Remove from the heat and transfer the chicken to a large bowl. Strain the broth through a fine-mesh sieve into another large bowl