2. Turnips that are sufficiently young and tender need only be rinsed and dried before cooking; older purple-top turnips will need to be peeled. Cut the turnips into halves, or quarters if they are small. Big ones should be cut in half lengthwise and the halves sliced into wedges.
3. Toss the turnips in a bowl with the olive oil and salt and pepper. Spread them out in an even layer on a baking sheet and roast them for about 10 minutes, then toss them once (if tossed more frequently, they tend to break apart as they become tender).
4. Roast for 5 minutes more and check for doneness - depending on the water content of the turnips, they can take from 15 to 30 minutes. The turnips are done when they are fork tender and nicely caramelized (golden brown).