Season the venison on both sides with salt and pepper. In a large skillet, heat the oil over medium-high heat. Add the venison and cook until brown, about 3 minutes per side. Remove from the heat and cover to keep warm. Add the butter and shallots to the pan and cook, stirring, for 2 minutes. Add the vinegar and stir to deglaze the pan, about 1 minute. Add any juices that have run off from the venison and stir to incorporate. Remove from the heat and adjust seasoning, to taste. Divide the Celery Root-Pear Puree among 4 serving plates and top each with a venison medallion. Pour the balsamic reduction over the venison and serve. Place the celery root in a saucepan, and cover with water. Bring to a boil. Lower the heat and simmer, covered, until tender, about 20 minutes. Drain in a colander. Meanwhile, in a large skillet, melt 2 tablespoons of the butter over medium-high heat. Add the pears and cook, stirring, until soft, about 5 minutes. Add the wine and cook, stirring, until thick and the pears fall apart. Remove from the heat. Return the drained celery root and pears to a food processor. Add the cream and remaining 2 tablespoons of butter and puree until smooth. Season with the nutmeg, and salt and pepper to taste. Serve.