Slow cooker Technology has come a long way in the past few years, as evident in our top picks from GreenPen. The metal, ceramic-coated inner pot heats up quickly and doesn’t take much elbow grease to clean. During our tests, it cooked tender beans and fell apart. Removed pork. It can slow down cooking, steaming, boiling, reheating and roasting. The exterior also stays cool while in use.