Clay-Pot Miso Chicken

From www.epicurious.com

Makes 4 generous (main course) servings

2 1/2 lbs chicken thighs, with skin and bone
½ c wood ear mushrooms
5cups water, divided
About 2 cups reduced-sodium chicken broth
1stalk burdock root (sometimes called gobo)
1/2 teaspoon distilled white vinegar or fresh lemon juice
1 and one 1/2 tablespoons canola oil
1 large onion, coarsely chopped
1 lb fresh shiitake mushrooms, stems discarded, large caps quartered
1 and one ½ tablespoons finely chopped peeled ginger
1 and one ½ tablespoons finely chopped garlic
1/2 cup mirin (Japanese sweet rice wine)
1/2 cup white miso (also called shiro miso)
1/4 cup soy sauce
1/2 lb mustard greens, tough stems and ribs discarded and leaves coarsely chopped (8 cups)

Accompaniment: steamed rice
Garnish: chopped scallions

Preheat oven to 500°F with rack in middle. Pat chicken dry, then roast, skin side up, in 1 layer in a shallow baking pan until skin is golden brown, 35 to 40 minutes. While chicken roasts, soak wood ear mushrooms in 2 cups water until softened, about 15 minutes. Drain in a sieve, then rinse well and discard any hard pieces. Drain well, squeezing out excess water.

Transfer roasted chicken to a bowl and pour pan juices through a fine-mesh sieve into a glass measure. Let stand until fat rises to top, 1 to 2 minutes, then skim off and discard fat. Add enough stock to bring total to 2 cups liquid. Reduce oven to 300°F and move rack to lower third. Peel burdock root, and, if more than 1-inch-thick, halve lengthwise. Cut crosswise into 1-inch pieces. Transfer burdock root to a bowl, then add vinegar and 1 cup water.

Heat oil in a 7- to 8-quart heavy pot over medium-high heat until it shimmers, then sauté onions until softened and beginning to brown. Add shiitakes, ginger, and garlic and sauté until garlic is golden, 3 to 5 minutes. Add mirin and boil, stirring and scraping up any brown bits, 1 minute. Stir in miso and soy sauce, then stir in chicken, wood ear mushrooms, burdock (drained), stock mixture, and remaining 2 cups water. Bring to a boil, skimming off any froth. Cover pot and braise in oven until chicken is tender, about 1 hour.

Stir in mustard greens and continue to braise, covered, 5 minutes. Serve in shallow bowls over rice.