Prick the London broil on both sides several times with a fork; place into a resealable plastic bag.

Whisk together the lemon zest, lemon juice, olive oil, sugar, green onions, Worcestershire sauce, Dijon mustard, salt, and black pepper in a bowl. 

Pour into the bag with the meat, coat with the marinade, squeeze out excess air, and seal.

Marinate in the refrigerator at least 3 to 4 hours, but overnight is best.

If you want it to look like the one in this image then Preheat an outdoor grill for medium-high heat, and lightly oil the grate. I personally cook this on a stove to get the full flavor. (From what I read you can't taste it that much on a grill) But I guarantee you will taste it on the stove! So put the oil in a skillet and putting it on medium high. Your choice :)

Remove the beef from the marinade, and shake off excess. (If cooking on grill then Discard the remaining marinade. But if on stove save it)

This part is for the grill. If cooking it on a stove go to the next step. Cook the beef until it is beginning to firm, and is hot and slightly pink in the center, about 17 to 20 minutes per side. An instant-read thermometer inserted into the center should read 140°F (60 degrees C). Cover the meat with two layers of aluminum foil, and allow to rest in a warm area for 10 minutes before slicing thinly across the grain.

Grab your meat and place it on the skillet. Let it cook on both sides until brown. Add the rest of the marinade and let the meat soak in the flavor. After 15-20 minutes cut in the middle to see If it's no longer pink. Or if you like it medium rare then your plate is ready 😀

P.s. onion tastes delicious!