Grilled Chicken Tacos

Ingredients

• 1 teaspoon plus 2 tablespoons olive oil, divided
• 1 (15-ounce) can black beans, rinsed and drained
• 1/2 medium white or red onion, cut into 1/2-inch dice
• 2-4 green serrano chiles, finely chopped
• 2 medium tomatoes, cut into 1/2-inch dice
• 1/2 cup chopped fresh cilantro, including stems
• Juice of 1 lime
• 1/4 teaspoon salt
• 2 boneless, skinless chicken breast halves
• 1/4 teaspoon freshly ground black pepper
• 8-12 white corn tortillas