Cook rice according to package directions. In a small bowl, combine 1 tablespoon cornstarch and the seasoning blend; sprinkle over chicken on both sides.
In a large skillet over medium heat, brown chicken in oil. Remove and keep warm. Add mushrooms and onions to the pan; cook and stir for 3 minutes. Add the vinegar, garlic and capers; cook and stir 2 minutes longer.
Return chicken to the pan; carefully add the broth, bay leaf and thyme. Bring to a boil. Reduce heat; cover and simmer for 10 minutes or until a thermometer reads 170°.
Combine the remaining cornstarch with the water until smooth; stir into the pan. Bring to a boil; cook and stir for 2 minutes or until thickened. Discard bay leaf. Serve chicken and mushrooms with rice.