Procedure
Heat a saucepan with olive oil in it. Add chopped onion and stir for 5 minutes. Add the pinto beans, beans, corn, diced tomatoes, water, and taco seasoning in it. Bring the mixture to boil. Lower the heat and cook for over 10 minutes, while stirring it occasionally. Add cooked chicken pieces and cook for 2 minutes more. Serve it hot.