A great hamburger is so wonderful. I I could eat hamburgers every day! So many places claim to have "The Best" Hamburger but do they really? Ground beef is made from beef trimmings. These beef trimmings are a natural by product from cutting up the beef carcass. Beef trimmings are most commonly sorted into 85's (85% lean), 65's and 50's. So to make an 80-20 (80% learn, 20% fat), a processor mixes 85's and 65's or 50's to get an 80% lean product. As beef prices rise or to have an even tastier burger, some places are going to 75% lean burgers. Also, you can buy beef subprimal cuts that are ground up like a ground chuck or a sirloin/brisket mix. My favorite is a grind with chuck/sirloin/brisket. But that gets pricey unless your customers will pay $15 for a hamburger meal. Watch out for beef trimmings that come off of aged steak cutting production. While this "ground steak" burger seems appealing, it cannot beat the fresh flavor of a burger made with fresh beef trimmings (I know, I have done thousands of these blind cuttings). Be sure to cook your burgers to 160 degrees F, as E Coli dies at this temperature. Use a meat thermometer to measure the temperature on at the center of the patty.