Season chicken with 2 tablespoons Knorr® Tomato Bouillon with Chicken flavor. Heat oil in large deep skillet over medium-high heat and brown chicken, in batches if necessary, turning once, about 4 minutes; remove chicken with slotted spoon and set aside.
Add onion, tomatoes, celery, green pepper, cilantro and oregano to chicken drippings in skillet and cook over medium-high heat, stirring frequently, until onion is golden and tender, about 10 minutes.
Stir in water, frozen vegetables, chicken and remaining 1 tablespoon Bouillon and bring to a boil over high heat. Stir in rice; reduce heat to low and simmer covered, until rice is tender and chicken is thoroughly cooked, about 25 minutes.
Remove chicken and set aside until cool enough to handle, about 5 minutes. Shred chicken into bite-size pieces; discard skin and bones. Stir chicken into rice.