Guacamole with Roasted Tomatillos

Name: Guacamole with Roasted Tomatillos
Yield: About 4 cups
Ingredients: 12 medium tomatillos (about 1 1/4 pounds), husked, rinsed; 1/2 cup finely chopped white onion; 1/2 cup finely chopped fresh cilantro; 4 serrano chiles, seeded, minced (about 2 tablespoons); 2 tablespoons fresh lime juice; 2 pounds avocados (about 3 large), peeled, pitted, coarsely chopped