Sara Moulton publishes a recipe for sautéed pork loin with mustard and grapes on her site at SaraMoulton.com. The recipe calls for pork loin, flour, onion, grapes and dry white wine, and makes four portions.
Cut a 1 1/2-pound boneless pork loin into eight 1/4-inch thick slices. Tenderize the pork slices by setting them between two sheets of plastic wrap with some water and pounding them with a rolling pin. Dredge the pork slices in a mixture of 1/2 cup all-purpose flour, 1 1/2 teaspoons of kosher salt and 1/2 teaspoon of freshly ground black pepper, shake off the excess flour, and fry four pork slices in a hot pan with 1/2 tablespoon of unsalted butter and 1 tablespoon of vegetable oil. Cook for two to three minutes on each side until slightly browned, then transfer the pork to a plate and cover loosely with foil. Repeat the process for the remaining four pork slices.
Add a small chopped onion and 1 cup of halved seedless grapes to the pan, reduce the heat to medium and cook while stirring for about five minutes. Bring the heat to high, pour in 1/2 cup of dry white wine and boil to deglaze the pan. Scrape up the browned bits until the liquid reduces to 1 tablespoon. Add 1 1/2 cups of chicken stock and 1 packed teaspoon of dark brown sugar; boil until it reduces by half.
Add the pork back to the pan, simmer for three to five minutes, then transfer to a large warmed plate. Whisk 1 1/2 tablespoons of Dijon mustard into the sauce, season with salt and pepper, and pour over the pork.