Position a rack in the center of the oven and heat the oven to 500°F.
Pat the pork dry, rub it with the oil, and season generously with salt and pepper. Heat a heavy-duty 12 inch skillet over medium-high heat until very hot, and then sear the pork on all sides until golden brown, about 6 minutes total. Transfer to a small rimmed baking sheet and roast until an instant-read thermometer inserted into the thickest part registers 140°F, 10 to 15 minutes. Transfer the pork to a cutting board, tent with foil, and let rest for 5 minutes.
Meanwhile, melt 1 Tbs. of the butter in the skillet over medium-high heat. Add the pears in a single layer and cook, flipping once, until just tender and lightly browned, about 3 minutes per side. Transfer to a plate and keep warm.
Add the remaining 1 Tbs. butter and the shallots to the skillet and cook, stirring, over medium heat until the shallots are just beginning to turn golden, 2 to 3 minutes. Add the vinegar and stir, scraping up any brown bits. Add the cider and cook until slightly reduced, 2 to 3 minutes. Whisk in the heavy cream, mustard, and thyme and cook until slightly thickened, about 3 minutes. Season to taste with salt and pepper.
Slice the pork and serve with the sauce and pears.