I've been making this for years. I try to make enough so I can have hot beef sandwiches with leftover roast and add cream of mushroom soup & cheese with the leftover potatoes,carrots, mushrooms & onions for another day's side dish. I don't really measure much so change amounts to fit pot
Place potatoes in pot first, then carrots, mushrooms and 3/4 of the onion.
Lay roast on top and season with worcestershire sauce, lawry's seasoning, salt & pepper to taste. Top roast with the rest of the onion. Add au jus base around the roast in pot. Add 3-4 cans beer to cover roast. Cook on low for 8 hours