Toss the tomatoes with the salt to begin drawing out their moisture and flavor. Sauté the shallot in canola oil over medium high heat until translucent. Add the tomato and any liquid that's leached out to the pan and cook stirring for a minute or so to heat the tomato and reduce some of the liquid. And the mustard and vinegar and stir to combine. Whisk in the oil until incorporated then remove the pan from heat. Taste for seasoning, add salt or vinegar as needed. Spoon over chicken, fish or vegetables.
From Ratio: The Simple Codes Behind the Craft of Everyday Cooking by Michael Ruhlman. Copyright © 2009 Scribner.
Michael Ruhlman is an author, writer and food blogger. His books include Ruhlman's Twenty, Ratio: The Simple Codes Behind the Craft of Everyday Cooking, The Elements of Cooking: Translating the Chef's Craft for Every Kitchen and The Making of a Chef: Mastering Heat at the Culinary Institute of America, as well as several cookbook collaborations and non-fiction books.