For the rub:
2 tablespoons herbes de Provence
1 tablespoon minced garlic
2 teaspoons kosher salt
1/4 teaspoon freshly ground black pepper
1 flank steak, about 1-1/2 pounds and 3/4 inch thick
For the marinade:
2 tablespoons extra-virgin olive oil
1/4 cup finely chopped shallots
1-1/2 cups hearty red wine
1 tablespoon tomato paste
1 tablespoon coarsely chopped orange zest
1 bay leaf
2 large portabello mushrooms, base of stems trimmed
1. To make the rub: In a small bowl combine the rub ingredients and mash together with a fork.
2. Trim the flank steak of any surface fat and rub the spices into the both sides of the steak. Place the flank steak in a shallow rectangular baking dish, cover, and refrigerate for 1 hour.
3. To make the marinade: In a medium saucepan over low heat, warm the olive oil. Add the shallots and cook until softened but not browned, stirring occasionally, about 3 minutes. Add the rest of the marinade ingredients, stir to blend and then heat to boiling. Reduce heat and simmer for 5 minutes. Set aside to cool.
4. Remove the baking dish from the refrigerator and place the mushrooms in the dish with the steak. Pour in the cooled marinade, and turn the steak and mushrooms several times to distribute the marinade. Refrigerate 1 to 2 hours, turning the steak and mushrooms occasionally.
5. Allow the steak and mushrooms to stand at room temperature for 20 to 30 minutes before grilling. Remove the steak and mushrooms from the dish and reserve the marinade. Pour the marinade through a sieve into a medium saucepan. Heat to boiling. Boil, over medium-high heat, until reduced by half. Keep warm over very low heat.
6. Grill the steak and mushrooms over Direct Medium heat until the internal temperature of the steak reaches 140 F for medium rare and the mushrooms are tender, turning once halfway through grilling time. The mushrooms will take 12 to 14 minutes and the steak will take 10 to 12 minutes. Transfer to a cutting board and let the steak and mushrooms rest for a few minutes before cutting into 1/4-inch diagonal slices. Serve with the hot marinade drizzled over the top along with sliced grilled tomatoes and grilled French bread, if desired.