Heat the oven to 350 degrees F and arrange a rack in the middle.
Mix together sherry, oyster sauce, and brown sugar until evenly combined; set aside. Pat ribs dry with a paper towel and season well with salt and five-spice powder.
Place a 3-quart Dutch oven or other heavy-bottomed, shallow pot with a tight-fitting lid over medium heat and add oil. When oil starts to smoke, add ribs and sear until well browned, about 2 minutes per side.
Remove ribs to a plate and set aside. Discard all but 1 tablespoon drippings, return pan to stove, and add garlic, ginger, and chile and cook just until fragrant, about 30 seconds. Stir in reserved sherry mixture and bring to a simmer.
Return ribs to pan and bring to a simmer. Cover and transfer to oven to cook, turning occasionally, until meat is knife tender, about 1 1/2 hours. Increase oven to 400 degrees F and cook, covered, until ribs are sticky, about 30 more minutes.