Flavor – How to get more flavor in the interior of a brisket

Sous vide not only keeps the proteins (main component) at a lower temperature, but also the spices/oils/flavorings. Heat helps release the taste and aroma of all the ingredients, and the sous vide might not be hot enough to do that.

So, while it kind of kills the simplicity, you could always sautee the seasonings in oil before adding them to the sous vide bag (not until cooler though). Or just keep them separate and recombine for serving. Sous vide itself (not the vacuum part) is mainly for maintaining/achieving a controlled internal temperature, and skilled cooks don't only sous vide a dish; they might sous vide and then finish under a broiler for texture, or with a torch. If the sauce isn't working inside the bag, make it work outside the bag.

Alternately, put the ingredients in the bag the day before, and let them marinate overnight in the fridge. The vacuum action is essentially just a speeded up marinade, so this should do the same.

Also, make sure you're using enough (but not too much) SALT.

Finally, call the Sous Vide Supreme company. They know their product's capabilities and limitations and might have some good recommendations.

Just my guesses.

Getting the Vanilla from the bean to the taste bud takes time. While many will advocate the use of fresh vanilla beans (as you have tried), I have always preferred the flavor that is granted from a good vanilla extract. In my opinion it is stronger and better distributed throughout the dish. Whether you buy or make your own extract I think you will get a more consistent and rich flavor that way.

(note: thanks to @rfusca for providing the extract link in a previous question)