The immersion blender is the opposite of the one-off tool. It’s a blender on a stick that you can put right into a mixture, hot or cold, press a button, stir it around, and purée the whole shebang. It’s brilliant, and for some of us, the number of times I feel sure I would have burned myself transferring hot soups to a blender to purée pays for the immersion or stick blender over and over again. All of this is to say, buy one if you use your food processor or blender with any regularity, and you’ll find yourself reaching for it often.