Preheat the oven to 350°F

Add the flour, salt and pepper to a shallow dish and whisk together. Add the tenderloin, turning to coat it completely, shaking off any excess.

In a heavy-bottomed pot or Dutch oven, over medium-high heat, add the olive oil and when it is hot add the pork and sear, turning to brown on all sides, about 4-5 minutes. Transfer the pork to a plate lined with paper towels to absorb any oil.

Add the shallots and garlic and cook for 1-2 minutes. Add the cider, scraping the bottom to remove any browning bits. Add the rosemary, thyme and mustard to the skillet, increase the heat and bring the mixture to a boil, stirring often. Return the pork to the pan, cover and transfer to the oven and cook for 20 minutes. Remove from the oven and add the apple quarters and continue to cook, covered, in the oven for an additional 15 minutes until the apples are slightly soft but still firm and the pork registers 145°F on an instant-read thermometer.

Transfer the apples and pork to a plate and allow to rest for 10 minutes.

While the pork is resting, place the pot over medium-high heat and bring the liquid to a boil, if it is very thin then allow it to reduce by 1/3, whisk in the butter to make a glossy sauce. Transfer the sauce to a dish or pitcher.

To serve: Place the pork onto a cutting board and slice crosswise into 8 slices. Arrange the slices of pork on a serving platter with the apple slices and spoon the sauce over the pork.