Braised Chicken and Poblano Chiles

• 8 (6-ounce) bone-in, skin-on chicken thighs, patted dry
• 1 teaspoon black pepper
• 1 tablespoon kosher salt, divided
• 1 pound poblano chiles (4 to 5 chiles)
• 1 medium-size (about 10-ounce) yellow onion, thinly sliced (about 1 3/4 cups)
• 2 garlic cloves, finely chopped (about 2 teaspoons)
• 1 teaspoon ground coriander
• 1 (15-ounce) can diced tomatoes, undrained
• 1 cup water

Warm corn tortillas or mashed potatoes, for serving

1. Sprinkle chicken evenly with pepper and 2 teaspoons salt. Set aside.
2. Using kitchen tongs, char each poblano directly over a medium flame on a gas stovetop. Cook until skin is blackened, 2 to 3 minutes per side. (Alternatively, preheat oven to broil with rack about 7 inches from heat source. Place chiles on an aluminum foil–lined baking sheet, and broil until charred, 5 to 8 minutes per side.) Place chiles in a bowl; cover with plastic wrap, and let steam 10 minutes. Rub off skins from chiles, removing as much of the blackened skin as possible. (Don’t worry if all of the skin doesn’t come off.) Remove and discard stems and seeds. Slice chiles lengthwise into thin strips.
3. Place chicken thighs, skin side down, in a high-sided 14-inch skillet or Dutch oven with a lid. Cook over medium, undisturbed, until fat renders and skin is crispy and golden, 10 to 12 minutes. Flip chicken, and cook until lightly golden, about 2 minutes. Transfer chicken to a plate, skin side up; remove and discard all but 1 tablespoon of chicken fat from skillet.
4. Add onion to drippings in skillet, and cook over medium-low, stirring often, until just softened, about 5 minutes. Stir in poblanos, garlic, and coriander; cook until fragrant, about 2 minutes. Add tomatoes with their juices, 1 cup water, and remaining 1 teaspoon salt, and stir to combine. Bring to a simmer over medium-high. Add chicken, skin side up, to skillet; reduce heat to low, and simmer, covered, until a thermometer inserted in thickest portion of chicken registers 165°F, about 20 minutes. Remove lid, and cook until sauce thickens slightly, 20 to 25 minutes.
5. Divide chicken and sauce evenly among 4 plates. Serve with warm corn tortillas or mashed potatoes. If serving with mashed potatoes, stir 2 tablespoons of mustard into 4 cups mashed potatoes before serving.