Cut off the white film from the tenderloin. Heat the oil-butter mixture on medium heat. Rub the meat with salt and pepper, fry on the each side until golden brown, the meat should be pink in the middle. Remove the tenderloin from the pan, suate onion, garlic (passed through the press) and ham. Dry mushrooms with wet rag, cut or not ( if champignons are small), place into the pan and fry. Pour over the broth, add the sour cream, salt, tomato paste, mustard, season with salt and pepper. If the sauce is too thin,add the soaked cornstarch in the cold water. Cool the sauce, add chopped parsley. On the next day slice the tenderloin, place in the sauce and heat.