Start With Fresh Meat
Don't buy preground meat! Sure, it's convenient, but if you have a food processor, you can grind the meat yourself. Buy 1/3 pound of meat per burger, preferably sirloin steak tips as they contain less connective tissue and fat than chuck. This recipe calls for 1 1/2 pounds of meat, forming four burgers. Cut it into 1/2-inch cubes and lay flat on a rimmed sheet tray. ATK recommends freezing tablespoons of unsalted butter too. You'll need 4 tablespoons per 1 1/2 pounds of meat. Freeze this for 35 minutes.
If you're wondering why butter? It turns out Chef Gordon Ramsay swears it's the secret ingredient that makes the best-tasting burger. The butter, though completely optional, creates more flavor and keeps the meat ultrajuicy.