6 (6-inch) corn tortillas, preferably a little old and dried out
1/4 cup corn oil, peanut oil, or extra virgin olive oil
1/2 cup chopped onion
2 cloves garlic, minced
1 medium Anaheim, poblano or jalapeño chili, seeded, veins removed, chopped (Depending on the hotness and flavor desired. You can also mix chilies—1 Anaheim and a 1/2 jalapeño.)
4 cups chicken broth or homemade chicken stock
1 (14.5-ounce) can crushed tomatoes (preferably fire-roasted)
1/2 teaspoon coarse salt (kosher or sea salt)
1 1/2 cups shredded cooked chicken
1 ripe avocado
1/2 cup (2 ounces) shredded Monterey Jack cheese (or mild cheddar)