Season the Chicken: Begin by patting the chicken thighs dry with paper towels. Sprinkle them evenly with kosher salt, black pepper, and chili powder. This early seasoning helps the meat develop deep flavor while cooking.
Sear Until Golden: Heat olive oil in a large skillet over medium heat. Place the chicken thighs in a single layer and let them cook until a golden crust forms on the first side. Flip and cook the second side until lightly browned. Transfer the chicken to a plate.
Build the Peach Sauce: Add another drizzle of olive oil to the same skillet. Stir in garlic and jalapeno slices, letting them soften slightly. Add peach preserves, soy sauce, Dijon mustard, and apple cider vinegar. Stir gently until smooth and glossy.
Add Fresh Peaches: Slide the sliced peaches into the skillet and let them simmer briefly. The fruit softens and releases juice that blends into the sauce, creating a sweet savory base.
Simmer Everything Together: Return the chicken thighs to the pan, nestling them into the sauce. Spoon sauce over the top, cover, and let everything simmer until the chicken cooks through and turns tender.
Finish and Rest: Sprinkle red pepper flakes over the skillet and let the dish rest for a few minutes off heat. This short rest helps the sauce thicken and settle around the chicken.
