Coat a 12-inch nonstick skillet with cooking spray; set over medium-high heat.

In a small bowl, combine flour with pepper; sprinkle over chicken. Brown chicken in a single layer in prepared skillet until golden on bottom, about 6 minutes; flip and brown on second side, about 4 minutes more. Remove chicken from skillet; set aside. (If necessary, brown chicken in two batches.)

Pour broth into skillet and scrape up any browned bits with a wooden spoon. Return chicken to skillet, cover and reduce heat to low; simmer until heated through, about 3 minutes. Stir in lemon juice and capers; heat for 30 seconds. Yields 2 chicken thighs, 3/4 cup string beans and about 1 1/2 tablespoons sauce per serving.