Marinade and flank steak:
- 1 fresh lemon
- 1 fresh lime
- 2 tablespoons soy sauce
- 1 tablespoon rice wine vinegar
- 3 garlic cloves, lightly crushed with the side of a knife blade and quartered
- 1/4 teaspoon ground cloves
- 1 tablespoon fresh rosemary leaves, stripped from about 2 or 3 sprigs
- 1 tablespoon fresh thyme leaves, stripped from 3 or 4 sprigs
- 1/2 teaspoon black pepper
- 2 pounds flank steak
- 1/2 cup barbecue sauce of your choice
Mushroom onion demi-glace:
- 1 tablespoon grapeseed oil
- 1 red onion, minced
- 1 cup white mushrooms (about 3 ounces), cleaned and sliced
- 1 cup dry red wine
- 1 cup water
- 1 teaspoon beef base
- Salt and freshly ground black pepper
Microwave lemon and lime in a small bowl to release essential oils and set aside until they are cool enough to handle.
Add soy sauce and vinegar to blender, replace lid and turn on blender. Through the feed opening add, 1 at a time, the garlic, ground cloves, rosemary, thyme, and black pepper. Halve lemon and lime and leaving the blender running, squeeze juice from each through the feed opening.
Place flank steak in a nonreactive container, add marinade and coat steak. Pour barbecue sauce over and spread to coat. Cover and refrigerate for 2 hours.
Heat grill and sear each side of steak. Cook to your desired level of doneness and transfer to a cutting board to let rest for 5 minutes.
Heat grapeseed oil in a skillet over medium-high heat. Add onion and saute until translucent, then add mushrooms and saute until they begin to give up their juices. Add red wine and allow most of it to evaporate. In a small bowl, whisk together water and beef base and add to pan. Allow to reduce by half. Season with salt and pepper to taste, remove from heat and keep warm.
Slice steak on the bias into 1/4-inch thick strips and arrange on plate. Spoon mushroom onion sauce over.