I haven't made steak in a while, but I did find a really good marinade. It's Herb Garlic from Newman's Own and it is delicious. I let it marinade overnight, which made the beef really tender.
Herb Garlic London Broil
1 1/2 lb. top round London Broil or flank steak
1/2 cup Newman's Own Herb Garlic Marinade
8 ounce container baby bella mushrooms
Place the London Broil in a large ziploc plastic bag. Add the marinade. Place the bag with the London Broil in the refrigerator; let marinate overnight.
Preheat broiler to low. Place the London Broiler on a broiler pan. Cut the mushrooms into quarters. Place the mushrooms on a large piece of aluminum foil and spoon some of the marinade from the plastic bag onto the mushrooms. Close up foil over mushrooms. Place the mushrooms in the bottom shelf of the oven. Place the London Broil in the oven. Broil the beef until desired doneness, about 30 minutes for medium well (about 150°F.).
Let beef rest for about 5 minutes before slicing. Place the beef on a cutting board and slice the beef against the grain into thin slices. Serve the sliced beef with the mushrooms.
(Each serving is 5 points.)