These humble root vegetables really shine in the winter; in frosty weather, the turnip plant converts more of the starch in the root into sugar, balancing their strong and peppery upfront flavor. Roasting turnips, alone or along with other root vegetables, brings out this natural sweetness. Good flavor pairings include apples, bacon, sage, mustard, and spices like cumin and coriander.
Don't confuse turnips with their larger and sweeter cousins rutabagas (though the two can often be substituted for one another). Turnips are usually white-fleshed, with white or white-and-purple skin, while rutabagas have yellow flesh.
Try substituting rutabaga or another white root vegetable, such as parsnips.
Look for turnips that feel firm and heavy for their size, with crisp flesh. Avoid turnips that are soft or flabby, or have brown, moist spots, which are signs of rot. Turnips tend to get woody as they grow, so the best ones are less than 4 inches in diameter.
Before cooking, peel off the skin and, on larger turnips, the outer layer of flesh. Plan to cook the turnips shortly after peeling, because their cut surfaces can discolor and develop off flavors if allowed to stand.
Store turnips in a plastic bag in the refrigerator for up to two weeks. If the turnips still have their greens attached, remove them before storing, because they can draw moisture out of the roots. The greens are edible, with a similar taste to collards, kale, or other hardy greens; if you'd like to cook the greens, store them separately.