4 servings (serving size: 1 chicken breast half and 2 tablespoons sauce)
Place each chicken breast half between 2 sheets of heavy-duty plastic wrap; pound to 1/4-inch thickness using a meat mallet or small heavy skillet. Sprinkle chicken with salt and pepper.
Heat oil in a large nonstick skillet coated with cooking spray over medium-high heat. Add chicken; cook 4 minutes on each side or until browned. Remove from pan; keep warm.
Add chicken broth, sugar, 2 tablespoons juice, and mustard to pan; cook over medium heat, scraping pan to loosen browned bits.
Combine water and cornstarch in a small bowl. Add cornstarch mixture to pan; stir well with a whisk. Bring to a boil over medium-high heat; cook 1 minute or until sauce thickens slightly. Whisk in remaining 1 tablespoon lime juice and butter, stirring until butter melts. Return chicken to pan; simmer 2 minutes or until chicken is thoroughly heated.