Take a knife and make small slits in the London Broil. Put the garlic slices in those slits. Set aside.
In a large bowl, put the Worcestershire sauce, olive oil, and red wine. Mix together.
Put the rosemary sprigs in the bottom of the container in which you are going to marinate the meat.
Fresh Rosemary in Red Wine Marinade
Put the garlic studded meat in the container, and pour the liquid over it, making sure it is completely submerged. If it isn't, add more wine until it is. Marinate, covered, in the refrigerator at least two hours or overnight.
Garlic-studded London Broil Marinating in Red Wine
Remove the meat from the marinade and set it aside, lightly covered. Remove the rosemary springs and set them aside as well. Do not throw away the marinade.
For an Outdoor Grill
Set up your grill for the indirect method. Put some or most of the marinade into a drip pan that will be surrounded by the coals.
When the coals are ready, if you want, put soaked wood on the coals.
Put the rosemary sprigs on the grate, over the drip pan. Then put the London Broil on top of the rosemary sprigs.
Grill the London Broil for five minutes on one side, with the grill covered.
Turn the meat over, keeping the rosemary on the grill.
Grill the meat covered until it reaches the desired temperature when checked with an instant-read thermometer, about 20 more minutes.
For an Indoor Cast Iron Grill
Put the flame under the grill on high and let the grill get to almost smoking. Use a brush to brush some oil on the grill then reduce the heat to medium.
Put some the reserved rosemary on the grill and top with the meat, and put the rest of the rosemary on top. Get a large cover, like for a wok or graniteware roaster and cover. Cook the meat for about 10 minutes, then flip making sure the uncooked rosemary goes on the bottom. Cover and continue cooking until the meat is to your liking.
For Sous Vide
Cook the meat in the marinade to the desired temperature, then grill it with the rosemary on a cast iron grill.
Remove from the grill, and let rest lightly covered for 5 minutes before carving. Cut the meat against the grain.
For the mushrooms
Put all the ingredients in a large bowl and let them marinate while the grill is getting ready.
Put the mushrooms in a pan and cook them for about 10 minutes or until they have softened and browned.
Notes
Use a pretty good red wine for this. A nice Chianti, Cabernet, Shiraz or Burgundy would be nice.
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