The sweet, delicately flavored pale yellow flesh of rutabagas pairs beautifully with potatoes and transforms a classic mash into a far more intriguing side dish. Add sour cream and flecks of fresh dill and serve with a holiday bird or with a simple roast chicken for a Sunday supper. I turn leftovers into a hearty brunch main course by reheating the mash, mounding it in a warmed wide bowl, and placing two poached eggs on top. Pass the hot sauce or offer some grated cheese for sprinkling.