Dinner: Udon with Preserved Mustard Greens and Chile Sauce

Ingredients

12 ounces mustard greens, stems discarded and leaves torn
Kosher salt
One 3-pound chicken, cut into 12 pieces
One 4-inch piece of kelp or kombu, rinsed
2 Fresno chiles—stemmed, seeded and thinly sliced
1 tablespoon Asian fish sauce
1 tablespoon fresh lime juice
1 tablespoon mala sauce or other preserved chile flakes in oil (see Note)
Two 8-ounces packages frozen udon noodles

Instructions

In a large bowl, toss the mustard greens with 1 teaspoon of salt. Gently massage the greens until just starting to wilt. Let stand at room temperature for 20 minutes, tossing occasionally. Gently squeeze the excess water from the mustard greens and drain well. Transfer the greens to a 1-pint glass jar, cover and let stand at room temperature for at least 4 hours or overnight.
Meanwhile, in a large saucepan, cover the chicken and kelp with 12 cups of water. Add a generous pinch of salt and bring to a boil. Simmer over low heat until the broth is richly flavored, about 2 1/2 hours, skimming off the foam as it rises to the surface. Strain the broth through a fine sieve into a heatproof bowl; you should have about 4 cups. Reserve the chicken for another use. Return the broth to the saucepan, cover and keep hot.
In a small bowl, whisk the Fresno chiles with the fish sauce, lime juice and mala sauce. Season lightly with salt.
In a large saucepan of boiling water, cook the udon until tender, about 2 minutes. Drain well and transfer to 4 warm bowls. Ladle the hot broth over the udon and top with some of the preserved mustard greens. Serve hot, passing the chile sauce at the table.