Don't judge roasts or burgers by appearance. Use a meat thermometer.
An instant-read meat thermometer ensures perfectly cooked burgers. A beef, veal, lamb, or pork burger cooked to 160 degrees F, regardless of color, is safe. (Ground turkey or chicken burgers must be cooked to 165 degrees F). If the beef has been mixed with eggs or other ingredients, grill the burgers to 165 degrees F.
If using a digital instant-read thermometer, insert the tip of the thermometer into the burger at least 1/4 of an inch for 10 seconds. If using a dial instant-read thermometer, insert the thermometer through the side of the burger to a depth of 2 to 3 inches to get an accurate reading.
A meat thermometer guarantees perfectly grilled roasts every time. Insert an oven-going meat thermometer into the center of the thickest part of the uncooked roast. The thermometer should not touch any fat, bone, or the pan. When the meat reaches the desired doneness remove it from the grill. Let it stand about 15 minutes before slicing. This will make the meat easier to slice.