Roasted Beet Salad with Walnuts and Walnut Oil

These beets are roasted, and very delicious! But if you have a mandoline, a professional tool that will slice vegetables evenly and very thinly, skip the roasting process and slice the beets raw (this works only with beets at the peak of seasonal freshness—sweet, dry, and tender). When really fresh beets are sliced so thin as to be almost shaved, there is no need to cook them. Toasted walnut oil adds a classic French flavor to the salad, but you could also use almond or pecan oil, available online and at gourmet or specialty markets. Store nut oils in the refrigerator; they turn rancid fairly quickly.