To me raw ones taste rather like radushes without the bite. Cooked, they taste like, well.........turnips. You'll just have to give them a try. If you find their flavor is too strong, Julia Child, in "Mastering the Art of French Cooking" says to blanch them in boiling, lightly salted water for 3 to 5 minutes. Then place in a pan with butter and chicken stock to barely cover; braise for 20 to 30 minutes or until tender but still hold their shape. If there is any liquid left, raise the heat and cook it off.
To serve add a little butter, parsley and a squeeze of lemon juice.
They're also good braised in the juice along side a pork roast. MMM.