From Charleton House, a country house hotel in Somerset, England, comes this piquant accompaniment to robust cheddar cheeses with good age and big flavors. We like it, too, with honey-glazed ham, in Christmas turkey sandwiches, or tossed with grilled red peppers. Look for aged cheddars from Vermont, New York State, and England, but always taste before buying. Give the onions two weeks of mellowing. Make up in small crocks or canning jars for giving, or in larger ones for the family. Keeps about 8 weeks in a cool place.
Andrea Reusing is the creator of the restaurant Lantern in Chapel Hill, N.C., and author of the book Cooking in the Moment: A Year of Seasonal Recipes. In this installment of The Key 3, she shares with Lynne Rossetto Kasper the techniques behind three of her favorite recipes: Turnip Soup, Overnight Braised Short Ribs and Tomato Salad.