Preheat your oven to 400°F (200°C). Pat the pork tenderloins very dry with paper towels. Trim any visible silver skin and excess fat using a small sharp knife, removing the thicker pieces.

In a small bowl, mix together the kosher salt, black pepper, garlic powder, and dried thyme or Italian seasoning. Rub this seasoning mixture all over the pork tenderloins, pressing it gently into the surface. If possible, let the seasoned pork rest at room temperature for 15–20 minutes while you prepare the cherry marinade.

In a medium bowl, stir together 1 cup of the pitted cherries, 1/4 cup of the chicken broth, 2 tablespoons balsamic vinegar, 2 tablespoons maple syrup or honey, the minced garlic, Dijon mustard, and 1 tablespoon olive oil. The mixture will look loose and chunky. You may marinate the pork in this cherry mixture for up to 2 hours in the refrigerator, turning occasionally, or simply reserve it to spoon a little over the pork before roasting and to use as part of the sauce.

Heat the remaining 1 tablespoon olive oil in a large oven-safe skillet over medium-high heat. When the oil shimmers, add the pork tenderloins (let excess marinade drip off if marinated). Sear on all sides until well browned, about 2–3 minutes per side, 6–8 minutes total. You are building a crust, not cooking the pork through.

Turn off the heat. If you did not marinate the pork, spoon a few tablespoons of the cherry marinade over the top of the seared tenderloins. Transfer the skillet to the preheated 400°F (200°C) oven and roast for 12–18 minutes, depending on thickness. Begin checking at 12 minutes. The pork is done when an instant-read thermometer in the thickest part registers 145°F (63°C). If you do not have an oven-safe skillet, transfer the seared pork to a foil-lined baking sheet, spoon some marinade over the top, and roast as directed.

Remove the skillet from the oven and transfer the pork tenderloins to a cutting board. Tent loosely with foil and let rest for 10 minutes. This allows the juices to redistribute and keeps the meat moist.

Place the same skillet you used for the pork back on the stove over medium heat (or use a clean skillet if you roasted on a baking sheet). Add the remaining 1 cup cherries, the remaining 1/2 cup broth, 1–2 tablespoons balsamic vinegar, 1–2 tablespoons maple syrup or honey (start with the smaller amounts), and the thyme. Scrape up any browned bits from the bottom of the pan. Simmer for 5–7 minutes, stirring occasionally, until the cherries soften and the liquid reduces slightly. Taste and adjust the balance with more vinegar for brightness or more sweetener if the cherries are very tart.

If you prefer a thicker cherry sauce, whisk in the cornstarch slurry (cornstarch mixed with cold water) and simmer for 1–2 minutes more, until the sauce is glossy and lightly thickened. Turn off the heat and stir in the butter until melted for a richer, silky finish.

Slice the rested pork tenderloin across the grain into 1/2-inch thick medallions. Arrange on a serving platter or individual plates and spoon the warm cherry sauce generously over the top. Garnish with chopped fresh parsley or thyme and a pinch of flaky sea salt, if desired. Serve immediately.