What does the term "London broil" really mean?
Coined in the early 1930s at Keen's Chophouse in New York City, the term "London broil" doesn't refer to a particular cut of meat at all. Rather, it's a generic label bandied about by butchers to sell large, cheap, unfamiliar steaks that might otherwise be ignored by customers. Over the years, a number of different steaks have been called London broil. For a while, flank steak was the most common, but flank's popularity on the grill and in stir-fries bumped its price into the $6.99-a-pound range—a bit too rich for London broil territory. Nowadays, you'll mostly see the still-cheap (roughly $3.99 a pound) chuck shoulder steak, top round steak, and bottom round steak labeled as London broil.
FLANK: Good and beefy, but its recent popularity has inflated prices.
CHUCK SHOULDER: Great flavor, but multiple muscle groups make for "gristly," unattractive slices.
TOP ROUND: Though "mineral-y" with a "tire-like toughness," top round is appealingly beefy.
BOTTOM ROUND: Similar to top round, but its uniform shape makes it even better for grilling: our favorite.