The tenderest cuts of steak, like filet mignon, also happen to be well beyond the price range of the average diner. If you’re planning on cooking a tough cut like sirloin or top round, there are a few things you can do to help break down the connective tissue in the meat before you start cooking it. One, you can use a device called a meat tenderizer, which is basically a dozen or so tiny knives that poke holes into the steak and help to break up the tough muscle fiber network. Two, you can pound it thin using a mallet. Three, you can take the enzyme or acid route.
Certain enzymes break down protein and collagen in meat without compromising the muscle fibers. These are found in fruits like kiwi, papaya, and pineapple; those “meat tenderizer” powders you find in the supermarket usually contain one or more of these fruit-based enzymes. A marinade with the right amount of acid (usually from vinegar) can also tenderize a steak, but don’t go overboard: Too much acid and it’ll become even tougher.