Flank Steak Stuffed With Mushrooms and Feta Cheese

Ingredients

• 2 cups baby spinach
• 4 tablespoons capers
• 4 cups crimini mushrooms
• 1 cup low fat feta
• 1 pound flank steak
• 1 tablespoon olive oil
• 1 cup diced onion
• 0.25 cup red wine
• 1 tablespoon rosemary
• 1 pinch pepper
• 1 pinch salt