Preheat oven to 400 degrees. Cut tortillas into 1/2" strips using kitchen shears. Place on flat baking pan or stone. Bake 7-8 minutes or until crisp.
Meanwhile, chop onion using food chopper. Cut chicken into 1/2" pieces. Saute' onion, add garlic. Add cooked chicken, chili powder and cumin. Stir in broth, cilantro, tomatoes, corn and chilies. Bring to boil and simmer 10 minutes.
Divide tortilla strips among 4 bowls. Top with cheese. Ladle soup over tortilla strips. Garnish with a little sliced avocado, cilantro, cheese.