London Broils come in two different shapes. Both are thicker than a normal steak but one is Flatter like a thick looking skirt steak or and the other is a cubed cylinder. I tend to like the flatter ones better due to there being more surface area, therefore more char. BOTH ARE PICTURED BELOW.
Fork your meat. I usually hit all four sides with a fork about 8-10 times. I'll get the off the shelf sesame ginger marinade (Ken's I think). Put it in a ziplock with all of the marinade and leave on the counter. The MOST IMPORTANT THING about grilling beef is allowing it to get to room temp.
After an hour in the marinade, take it out and season it with garlic powder, onion powder, S N P.
Put your grill on HIGH.
Put meat on grill. Cover for 2 minutes. Rotate 90 degrees. Cover.
2 minutes. Flip. Cover
2 minutes. Rotate 90 and turn off grill and cover.
IF YOU DO THE CYLYNDRICAL ONE, CUT TIME BY 30 secs and do,all four sides.
After about 8 more minutes depending on the thickness. Take out and let rest.
Carve thinly at 22 degree angle.
It pairs best with my spaghetti ala carbonara (that's what you need to learn). But the normal trimmings will do.
What temp is "high"?