Skillet Chicken With Mushrooms and Caramelized Onions

Ingredients

• 10ml honey
• 5ml Dijon mustard
• 0.5g red-pepper flakes
• Kosher salt and black pepper
• 680g boneless, skinless chicken thighs, cut into 7.5cm pieces
• 340g cremini mushrooms, stems removed and thinly sliced
• 2 medium yellow onions, thinly sliced
• 75ml olive oil
• 30ml plus 10ml sherry vinegar
• 30g fresh flat-leaf parsley or dill leaves and fine stems, roughly chopped
• Bread or cooked pasta, for serving
• 25g grated Parmesan or pecorino (optional)

Instructions

1. Whisk 30 ml oil, 30 ml vinegar, the honey, mustard, red-pepper flakes and 5 g salt in a large bowl. Pat the chicken dry, season with salt and pepper and coat with the marinade. Leave at room temperature, stirring once while you make the onions.
2. Heat a 30 cm cast-iron or heavy skillet over medium-high until very hot, 1.5 to 2 minutes. Add the onions in an even layer, season with salt and cook mostly undisturbed for 4 minutes, stirring about once per minute. Add the mushrooms, season with salt and cook in the same way until they shrink and begin to brown, about 4 minutes.
3. Stir in the remaining 45 ml olive oil and cook until the onions start to color, about 2 minutes, lowering the heat if needed. Push the vegetables to the edges and add the chicken to the center. Pour any remaining marinade over the vegetables. Cook undisturbed for 4 to 5 minutes, then combine everything and cook, stirring occasionally, until the chicken is cooked through, about 10 minutes more.
4. Add the remaining 10 ml sherry vinegar, stirring and scraping up the browned bits from the bottom of the skillet. Season to taste with salt.
5. Remove from the heat and top with the parsley and cheese, if using. Serve with bread or pasta.