I deep-fry in soy oil because it is lighter than other oils and it’s inexpensive, so I can change it often. That unappealing greasy fried flavor comes from oil that has been reused one time too many. I usually don’t reuse oil more than once, if at all, and only when working with the same kind of ingredient—you wouldn’t, for example, want to fry something sweet in an oil that you’ve previously used for frying fish. You want to fry most things between 350° and 375°F to achieve a greaseless, crisp crust. My preferred gadget for this task is an electric tabletop deep-fryer (Waring makes a good one). Some vegetable chips (beet and eggplant, for example) and onions that are naturally higher in sugar content are better off fried at a lower temperature to achieve crispness before they start to burn.