In a sauteuse or a small sauce pan, sweat the shallots down in 1 Tbl of butter over medium heat. Deglaze the pan with white wine. Reduce slightly. Throw in the Sauce Espagnole and the tomato sauce. Check for seasoning. Reduce the sauce - slowly - until it coats the back of a spoon. Stir in the mustard and cornichons. Bring the sauce up to temperature, then cut off the heat.