How to Make It
Heat a large skillet over medium-high heat. Add 1 1/2 teaspoons oil to pan; swirl to coat. Sprinkle chicken evenly with 3/8 teaspoon salt and 3/8 teaspoon pepper. Add chicken to pan; cook 4 minutes on each side or until chicken is done. Remove from pan.
Combine stock and mustard, stirring with a whisk. Add remaining 1 tablespoon oil to pan; swirl. Add remaining 3/8 teaspoon salt, remaining 3/8 teaspoon pepper, sage, rosemary, apple, and onion to pan; cook 4 minutes, stirring occasionally. Stir in stock mixture. Return chicken to pan; cook 3 minutes or until liquid is reduced by half.