Geoff and I had this last night, and it was really good. We used 2 pounds of pork tenderloin, since that was the packaged weight, and we didn't feel like reserving 1/2 pound for some other use. More leftovers!
Two 12-ounce pork tenderloins, cut into 2-inch lengths and pounded 1 inch thick
Salt and freshly ground pepper
1 teaspoon all-purpose flour, plus more for dusting
2 tablespoons unsalted butter
2 tablespoons extra-virgin olive oil
1 large onion, very thinly sliced
1 tablespoon grainy mustard (we used a coarse ground dijon)
1 cup low-sodium chicken broth
1 tablespoon chopped fresh dill (we used more, because I had some that needed to be used)
Buttered noodles, for serving (we served it with roasted sweet potato)
Season the pork with salt and pepper and dust with flour. In a medium, deep skillet, melt the butter in the olive oil. Add the pork and cook over high heat, turning once, until lightly browned, about 3 minutes. Transfer the pork to a plate.
Add the onion to the skillet, cover and cook over moderate heat, stirring occasionally, until softened, about 10 minutes. Stir in the mustard and the 1 teaspoon of flour and cook for 1 minute. Add the chicken broth and bring to a boil. Nestle the pork in the onion sauce. Cover and simmer over moderate heat until the pork is cooked through, about 8 minutes. Transfer the pork to plates. Stir the chopped dill into the sauce and spoon over the pork. Serve with buttered noodles.
Source: Food & Wine, February 2010