Now let's take that same piece of hanger steak and cook it sous vide. Salt and pepper it and seal it in a Ziploc bag (vacuum sealers work great for sous vide, which is, after all, French for under vacuum but they're not mandatory—as long as the bag doesn't float, you're good). Then toss it in your 55-degree Celsius water bath. If you've read your McGee, you know that cooking adheres strictly to the rules of science: muscle cells, fat cells, collagen and connective tissues all break down and tenderize at consistent and exact temperatures. As a result, we know that 55 degrees Celsius (no Fahrenheit! this is Science!) is the temperature of perfectly cooked medium rare beef. So toss it in, wait 45 minutes—or 4 hours, if that's more convenient, as the meat won't rise above 55 degrees—then pull it out. It may look gray and gross right now, but do not fear! We know that the entire piece of meat has cooked in nothing but its own delicious juices to the scientifically derived temperature of perfect medium rare beef. The antidote to the yucky grayness is a good hot sear afterwards: fire up your cast iron pan to a scary level of heat and blast it for just a minute on each side with a little butter or oil in the pan to add a tasty, crunchy crust. Or if you really want to please your inner mad scientist, use a blowtorch. Then eat the most insanely tender and perfectly cooked steak of your life.