The safest way to thaw London broil steak is to place the steak in the refrigerator and allow it to thaw slowly.
However, this can take hours; if you forgot to put the steak in the refrigerator in the morning, you won't have time to thaw your meat for dinner when you get home from work in the evening.
You may also try this method from Leaf.tv:
Step 1
Remove the London broil steak from its packaging.
Step 2
Place the steak in a plastic food storage bag and seal it. When closing, remove as much air as possible. You want the bag airtight.
Step 3
Set a large pan in the kitchen sink and fill it with cold water.
Step 4
Submerge the steak in the water and place a plate or similar heavy object atop the steak, to keep the meat under the water. Replace the water with cold water every half hour. It will take less than an hour for a pound of meat to thaw.
London Broil, despite what you might find at the local meat market, is not a cut of beef but rather a method of cooking a steak. Find out how to select and cook London broil at Thespruce.com.