Use some Johnny's French Dip au jus mixed with water, granulated garlic and fine grind black pepper and maybe a little worsty. Some people like to add some bacon fat too.
Or, use undiluted Campbell's consomme with garlic and pepper, etc.
No need for salt since the au jus or consomme has plenty in it already.
You could add some amesphos but you will probably have to order it.
One other option is to find some sort of broth or beef base that contains phosphates so you don't have to add them. There are a few brands around if you read the ingredients in some and you may find one in local stores. Some beef bases sold for restaurant use have phosphates in them.