If your burgers tend to fall apart on the grill, try using eggs, which act as a binding agent, holding the the otherwise crumbly meat together. You can also use eggs to unify your burgers if you add other dry ingredients to the mix, such as chopped onions or carrots.
Beat the egg. Mix it into the beef with your hands until the meat reaches a uniform texture. The resulting mixture should be moist enough that the beef is no longer crumbly but not so moist that it sticks to your hands in clumps.
Add the white of another egg if the mixture is too dry, mixing it gradually until you achieve the correct texture. If the mixture is too wet, add bread crumbs until only small amounts of ground beef stick to your hands. You may need as much as 1/2 cup bread crumbs before the beef reaches the proper texture.
Shape the meat into four patties for every pound of beef. Cook in a skillet or on a grill, turning once, for about 10 minutes. Insert the food thermometer into the side of the burger. If it reads 160 degrees Fahrenheit or higher, the burger is done. If not, continue cooking, checking every two minutes until you finish.
You can add moisture to an overly dry burger mix by adding tomato paste. This lacks the binding quality of an egg, but will moisten a burger that is still too dry after you mix in the egg. Try adding finely chopped onions or carrots to your burger mix to add flavor. The egg will bind the onions and carrots into the meat. Add no more than 1/2 cup of vegetables for every egg. If the mixture crumbles in your hands, add more egg to bind it together.