Fill a pot with water, and add chicken. Bring to a boil, reduce and simmer until completely cooked. When chicken is cooked, slice and spread mustard over the chicken, toss to coat, add about ¼ cup water. (Or you can use that rotisserie chicken!)
Mix the chicken, cheese, cilantro, spices and the avocados.
Spread 1 tablespoon sour cream on each tortilla, add 1/8th of the mixture, form a roll. Finish all burritos.
Heat 1 tablespoon oil into a pan and place all four tortillas on the pan, cook for 2 minutes on medium- high heat. Flip on the other side and cook for another minutes or until the the tortillas are golden. Serve warm.