Sauté onions and garlic in olive oil for approximately 3 minutes. Add frozen corn and sauté an additional 3 minutes. In a stockpot, combine onions, garlic, corn, chicken broth, chicken, beans, chiles, cumin, black pepper and red pepper. Cook over medium heat for approximately 20 minutes. Reduce heat to low. Mix cornstarch with water. Slowly add cornstarch mixture to chili stirring constantly. Cook for an additional 2 minutes as chili thickens. Top with chopped cilantro and serve.