1/4 cup all-purpose flour 1 teaspoon salt 1/4 teaspoon freshly ground pepper 4 (5-ounce) skinless chicken-breast halves, (without tenderloin) 1 tablespoon olive oil 1 tablespoon unsalted butter 1/4 cup white balsamic vinegar 2 clove garlic, crushed 1 cup dry white wine or chicken broth 2 teaspoon minced fresh rosemary 2 tablespoon grainy mustard 2 scallions, minced 1/2 cup pitted kalamata olives 1 teaspoon capers, drained 2 plum tomatoes, seeded, diced
Coat: Dredge 4 chicken breast halves in a mixture of 1/4 cup all-purpose flour, 1/2 teaspoon salt, and 1/4 teaspoon pepper, lightly coating both sides.
Dredge: In a large nonstick skillet, heat 1 tablespoon olive oil. Add 1 tablespoon unsalted butter; melt. Add chicken and sauté, 6 to 7 minutes, turning once. Remove chicken to a plate; keep warm.
Deglaze: Add vinegar and garlic to skillet, scraping up browned bits until reduced to 1 tablespoon, 1 to 2 minutes. Add wine and rosemary and cook, stirring frequently, 3 to 4 minutes, until slightly thickened and reduced by half.
Finish: Whisk in mustard and cook 1 minute. Add scallions, olives, capers, remaining salt, and tomatoes, stirring to combine. Pour over chicken.