This was amazing. The payoff was huge considering the amount of effort (almost none) and the number of ingredients (hardly any). I added some cloves of garlic in with the onions because I am a garlic fiend. At first I was nervous about the cranberry sauce but it really mellowed out during the cooking. Will definitely be making this again. Just make sure you plan ahead as it takes 2 days to marinate with the dry rub and then another day to let the fat settle.
I found this recipe in Stephanie Pierson's "Brisket Book." Highly recommended. Can't wait to try out more brisket recipes.