Chicken Tortilla Soup

INGREDIENTS

• 1 cup chopped onion
• 3 cups chicken broth
• 1 (14.5 ounce) can diced tomatoes with green chile peppers
• 1 envelope taco seasoning
• 1 1/2 pounds skinless, boneless chicken breast meat - cubed
• 2 tablespoons cornstarch
• 1/4 cup cold water
• 1/4 cup shredded Mexican cheese blend
• 1 tablespoon chopped fresh cilantro (optional)