In a medium bowl, combine the peach preserves, olive oil, soy sauce, lime juice, Dijon mustard, garlic, salt, black pepper, and red pepper flakes. Mix well until smooth and fully incorporated. Set aside.

Pat the chicken thighs dry with paper towels.

Season the chicken evenly with salt, pepper, and chili flakes.

Heat the olive oil in a large nonstick skillet over medium heat. Once hot, add the chicken thighs (work in batches if needed to avoid overcrowding). Cook for 5 minutes on one side.

Flip the chicken, reduce heat to medium-low, and cook for another 5 minutes, or until the internal temperature reaches 165°F.

Remove chicken from the skillet and set aside on a plate. Tent loosely with foil to keep warm.

Raise the heat back to medium. Deglaze the pan with a small splash of balsamic vinegar just long enough to lift the browned bits—about 30 seconds to 1 minute. Don’t add too much liquid, and let it mostly evaporate.

Add the sliced jalapenos to the same skillet. Cook for 2 minutes until softened.

Add the peach slices and cook for another 2 minutes, until they begin to soften and caramelize slightly.

Pour the prepared peach glaze into the skillet with the peaches and jalapenos. Stir well to coat everything evenly.

Return the chicken to the skillet and spoon the glaze over the top. Cook for 1–2 minutes more, just until everything is heated through.

Serve warm, garnished with fresh herbs or toasted nuts if desired.