The cook time for this recipe is based on a medium-well temperature. Adjust the time according to your preference. Add/subtract a few minutes to the cooking time and check for doneness with 5 minutes left to cook. To check the temperature of the London Broil, use a meat probe. Rare= 120-125 degrees Fahrenheit Medium Rare=130-135 degrees Fahrenheit Medium=140-145 degrees Fahrenheit Medium Well= 150-155 degrees Fahrenheit Well= 160 and up degrees Fahrenheit