Place the pork chops on a layer of paper towels and blot dry. Heat 2 tablespoons of the olive oil in a large, heavy skillet over high heat. Working in batches if neccesary, brown the tenderloin in the skillet, leaving at least an inch of space between each piece. Allow to cook undisturbed for 2-3 minutes on each side, until the bottoms are well-browned and are easily flipped. Turn them over and cook the other sides until golden. Transfer the cooked pork to a dish, and repeat with the remaining slices, addidg a bit more oil if needed. Be sure to leave the crusty brown bits in the pan when the pork is done.

In the same skillet, melt the butter and last tablespoon of oil over medium heat. Add the apples and onions, and toss to coat. Sauté, stirring occasionally, 4-8 minutes, until the apples begin to brown. Add the apple cider and brandy to the skillet. Bring to a boil and scrape the pan with a spatula to loosen any bits stuck to the bottom. Simmer over medium heat for 3-4 minutes, until the liquid turns thick. Increase the heat to high and add i/4 cup of water. If any juices have accumulated underneath the cooked pork, pour them into the skillet. Add the salt, some black pepper, then the thyme, rubbing the thyme between your fingers to release its oils. Boil 3-4 minutes until the liquid becomes syrupy. Add the cream, and continue to cook until reduced by half, 2-3 minutes. 
Reduce heat to medium. Transfer the pork medallions back into the skillet, turning to coat. Simmer 5-10 minutes, until cooked through (see note). Taste, and adjust the seasoning if needed. Arrange the pork on a serving platter and cover with apples, onions, and sauce.