You form perfect burger patties, only to have them bulge in the middle during cooking. As a result, the edges burn, you struggle after you flip them, the patty doesn't fit well on the bun, and your lettuce, tomato and onion don't sit properly on top. If you try to flatten your burger by pressing on it with a spatula during cooking, it loses all its moisture and becomes dry and tasteless. Take a step during prep to prevent this problem and keep your burgers flat as they cook.
One Little Indentation
When cold hamburger meat hits a hot surface, its edges contract. The meat in the middle must go up, so your burgers develop a dome. Make a depression in the middle of the top of your patties with one or two fingers or the back of a spoon. Don't make a deep hole; just give the patty a concave center. When the meat in the middle rises, it evens out the burger.
Other Tips
Season the meat before forming patties. Work with cold ground meat and cold, wet hands. Manipulate the meat as gently as possible; packing the meat densely yields heavy, dense burgers, while lightly packed meat yields juicier, lighter burgers. Shrinkage can't be avoided, so make patties that are 1/2 to 1 inch wider than your buns. Burgers about 3/4- to 1-inch thick are easier to crisp on the outside without overcooking the inside.