Ah, yes, the illustrious chateaubriand! Fillet mignon, fillet of beef, beef tenderloin, eye fillet, fillet steak: all of these names for the same cut of beef (though some refer to select portions of the whole tenderloin) that is prized for its tenderness. Originally, chateaubriand was a cut of sirloin, but it now ubiquitously refers to a large cut from the tenderloin of cattle. Tenderness is a consequence of how evenly spaced the muscle protein of meat is with either water, fat, or gelatin. Gelatin is derived from collagen, the compound responsible for the strength of connective tissue. Cooked over time, collagen breaks down into gelatin (as in Jell-o), its softer constituent.
A cut with high amounts of connective tissue (muscles that see a lot of work while the animal is alive) tends to require longer cooking to give the collagen time to break down into gelatin so that it will be soft instead of tough (think pulled pork or brisket). Both pork shoulder (typically used for pulled pork) and brisket are cooked well past “well done”, a state wherein enough water has been expelled to make the meats tough if not for their ample gelatin.
Beef tenderloin has little fat and connective tissue, so in order for it to be tender, it is necessary that enough of its water remains within the meat. Meat fibers, like all biological cells, hold water. As the temperature of the meat increases, the proteins that give structure to each fiber begin to denature, or ‘unfold’. As they unfurl, previously internal portions of their long amino acid chains are exposed, attracting other partially-unfolded proteins. The hotter they get, the more they are denatured, and thus the more attracted they become to one another. As they are drawn closer and closer together, the muscle proteins squeeze out the water between them much like the twisting of a wet rag releases more and more water the tighter it is wrung. You can see this effect as you cook a steak—water is forced from the surface of the meat into the cooking vessel.
Enter the sous-vide method and SmartHub! By maintaining a temperature of 127ºF, a perfect medium rare is achieved. This ensures that too much water is not pushed out of the meat by denaturation. While lovely by itself, we enjoy the ancillary flavors of a mildly-hopped beer and minced garlic with our beef.
To prepare this dish, we first smashed and minced garlic (the smashing assists with the removal of the papery outer layer) and added it to a vac-snap bag with about a cup of beer. We then added salt* and our beef to the bag. Depending on how thickly the meat has been portioned, the cooking time could be anywhere from 2-4 hours. Ours was done in about 3.
If you are preparing this for a party, it can be done about a week ahead of time. We prepared ours 3 days before we removed it from the refrigerated bag, patted it dry, and seared the outside in oil on high heat. This chateaubriand was served (lovingly to ourselves) with a splash of béarnaise and roasted brussels’ sprouts.
*Adding the appropriate amount of salt is not a terribly tricky thing if you understand the “path” of that salt. For example, if you salt pasta directly, you will use far less salt than if you were to salt the pasta water. First, the water dilutes the salt, and then when the pasta is drained (and potentially rinsed) even more salt is lost. In the case of our beef here, the salt is being diluted and dissolved by beer, which will then be poured off. The more beer that you add, the more salt you will need to offset that dilution.