When making hamburger patties from grass fed beef, don’t overwork the ground beef. The less you handle the meat, the better the burger’s consistency.
Cook the ground beef in much the same way as steak.
Sear it on both sides over the hot area of your grill, then move to a medium heat until reaching an internal temperature of 150°-155°F. Remove the hamburgers from the grill, cover loosely with foil, and let the burgers rest for 5-10 minutes. Juices are retained if the meat is allowed to rest.
The internal temperature should reach 160°, at which point it should be slightly pink inside.
Ground beef needs to be cooked throughout as all parts of it have been touched by the cutting blades of the grinding machine. Reaching the proper temperature is the only way to assure your meat is safe.
You may want to experiment a little, double checking with the thermometer.
When the burger starts to feel firm, it is about done. Cooking slower allows the internal portion of the burger to cook without drying out the outer part of the meat.
Do not press the burger while cooking, as it forces the juices out of the meat.
Also, keep your eye on the fire, as it is easy to over-cook the burgers, resulting in a very dry piece of meat.