In a Dutch oven or oven-proof covered pan, heat the oil over medium heat. Season the pork on all sides generously with salt and pepper. Brown the pork on all sides, about 4 minutes per side. Remove the pork from the pan and set aside.
Add the onion, apple, and pear to the pan. Season with a large pinch of salt and pepper. Cook until soft and beginning to brown, about 8 minutes. Pour in the cider, scraping the pan to release any of the brown bits at the bottom of the pan. Add the pork back into the pan. Cover and bake in the oven until the pork registers 145ºF on an instant read thermometer, about 40 minutes.
Remove the pork from the pan, place it on a cutting board, and tent with foil. Let sit for 10 minutes.
Puree the cider mixture in a blender. Pour back into the pan and bring to a boil. Season to taste with salt and pepper.
Slice the pork and serve with the gravy on the side.