London Broil ... Low and Slow or Sear? Tender ???

My wife made a slow cooker London broil pot roast recipe that smelled and looked amazing. I was gone that day for dinner so I brought it for lunch to work the next day. I heated it up and was walking to my desk when I dropped the entire meal all over the office. Like I said, it looked and smelled great.

Part of your confusion is probably the fact that "London Broil" isn't a cut of meat (it's a recipe/technique) although a lot of stores sell different cuts of beef labelled as "London Broil".  There's no telling what cut you're getting, it could be top sirloin, flank, top round, etc. 

So what one person says works for London Broil might actually be using a different cut of beef than what you have.  If it's flank steak, I just do a quick cook (450-500 x 4-5 min per side).  If it's a cut from up on the shoulder, it's going to take longer to tenderize so I'd do a slow roast or reverse sear type of cook.