From Chez Panisse VEGETABLES by Alice Waters
-Preheat oven to 425 degrees.
-Rinse and dry turnips (only older, purple top turnips need peeling)
-Cut the turnips into halves. Cut big turnips in half lengthwise and slice halves into wedges
-Toss turnips with a generous splash of olive oil, salt and pepper
-Spread in an even layer on a baking sheet and roast for about 10 minutes
-Toss them once and roast for an additional 5 minutes
-Check for doneness , they will take anywhere from 15 to 30 minutes depending on their water content. They are done when tender and nicely caramelized