In a medium bowl, combine the chicken, onion, tomatillo sauce, tomatoes, and pine nuts. Add the steamed broccoli and toss. Divide the chicken mixture among the flat bread or tortillas, top with the diced avocado, and roll up. Serve with the remaining avocado and lime wedges.Tip: Also called Mexican green tomatoes, tomatillos are tangy and fruity. Look for jarred tomatillo sauce in the international section of your supermarket.