Rinse the chicken and pat dry. Mix 1/4 cup flour, salt and pepper in shallow dish. Add the chicken; coat all sides. Discard the remaining flour mixture. Melt the butter in a 10-inch nonstick skillet over medium-high heat. Add the chicken. Cook until deep golden brown, turning to brown all sides. Cover and cook 15-20 minutes or until no longer pink in center and a thermometer inserted in thickest part reads 165°F. Remove to serving platter; cover to keep warm. Add the tomato, tomato sauce, garlic and remaining tablespoon of flour to skillet; cook over medium-high heat for 3 minutes or until thoroughly heated, stirring frequently with a wire whisk. Stir in the chicken stock; bring to a boil. Reduce the heat and simmer for 3 minutes. Stir in the sour cream with wire whisk. Cook, but do not boil, until thoroughly heated. Pour over the chicken. Garnish with fresh parsley, if desired.