Sprinkle the rosemary and thyme all over the pork tenderloin, pressing to adhere. Cut the pork crosswise into 1-inch medallions. Flatten the medallions slightly to form nice rounds. Season each medallion on both sides with salt and pepper.

Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the pork medallions in 1 layer, being careful not to overcrowd the pan (there should be some space in between each medallion; if your pan isn’t big enough, do this in 2 batches). Cook until golden brown on the bottom, about 3 minutes. Flip and cook until golden on the other side, an additional 2-3 minutes. Transfer the pork to a plate (reserve the skillet).

In the same skillet, heat 1 tablespoon olive oil over medium-high heat. Add the onions with a pinch of salt and pepper. Cook, stirring often, until the onions are lightly softened, about 2 minutes. Stir in the apples. Reduce the heat to medium; cover and cook, stirring occasionally, until the apples and onions are golden and tender, 4-6 minutes (if the drippings on the bottom of the pan start to look too dark, add a small splash of water). Transfer the apples and onions to the plate with the pork (reserve the skillet).

Put the pan back on medium heat and add the apple cider. Using a wooden spoon, scrape up any brown bits on the bottom of the pan. Increase the heat to high and bring to a boil. Reduce the cider by half (it should look slightly thickened). Whisk in the crème fraiche. Taste the sauce and season with salt and pepper. Add the pork, apples and onions back into the sauce (along with any juices on the plate) and stir to coat. Cook over gentle heat until the pork is cooked through and happily bathed in the sauce, about 5 minutes. Do Ahead: The pan can sit, covered (off the heat), for up to 30 minutes. Reheat gently before serving.

To serve, place a big mound of polenta on each plate or in shallow bowls. Arrange a few medallions of pork on top of the polenta, and spoon the sauce over. Pile a mound of slaw on top or alongside.