Roasted Pork Tenderloin with Fresh Plum Sauce

Preheat your oven to 400°F (200°C).

Heat oil in a large, oven-safe skillet over medium-high heat. Season the pork tenderloin generously with salt and pepper. Sear the tenderloin in the hot oil, turning to brown all sides, about 2 to 4 minutes per side. Remove the pork from the skillet and set it aside on a plate.

Sauté the onion with a pinch of salt in the remaining drippings in the skillet until the onion softens, about 3 to 5 minutes. Add the shallots and reduce the heat to medium. Continue cooking, stirring occasionally, until both the onion and shallots are golden and caramelized, about 10 minutes.

Add thyme to the onion mixture, then place the tenderloin on top. Arrange plums, skin-side down, around the pork. Transfer the skillet to the preheated oven.

Roast until the pork is slightly pink in the center, about 20 minutes. Use an instant-read thermometer to check that the internal temperature reaches at least 145°F (63°C). Remove the pork and plums from the skillet and transfer to a clean plate, covering with foil to keep warm.

Place the skillet over medium-high heat. Add water and vinegar to the onion mixture, scraping the browned bits from the pan with a wooden spoon. Bring the liquid to a boil and simmer until it reduces by half, about 5 to 10 minutes. Remove from heat and whisk in cold butter until melted and the sauce becomes glossy.