I got this recipe from my neice about a year ago....I love it....its great to make for company. If you are going to have a crowd I'd up the liquid so you have enough Au Jus to go around.
A bottom round roast works well as well as the brisket....want to jazz it up, add some sliced mushrooms. Generally I don't use the onion soup mix, I saute raw onions and add a tsp. of beef base. Browning the meat and deglaze the pan a must for great flavor.