Grilled Flank Steak with Creamy Mushroom Sauce

Ingredients

• 2 pound flank steak, fat trimmed
• 2 teaspoons Penzey’s Chicago Steak Seasoning
• 1 teaspoon olive oil
• 8 ounces shitake mushrooms
• 5 ounces crimini mushrooms
• ¼ teaspoon Penzey’s Sunny Paris Seasoning
• 2 Tablespoons nonfat plain greek yogurt
• 1 Tablespoon low sodium chicken or vegetable broth (optional)
• 2 Tablespoons chopped fresh chives