1. Preheat oven to 400°.
2. Heat a large ovenproof skillet over medium-high heat. Sprinkle chicken with 1/2 teaspoon salt and 1/2 teaspoon pepper; coat with cooking spray. Add chicken to pan, skin side down; cook 6 minutes or until skin is golden brown and crisp. Turn chicken over. Place pan in oven. Bake at 400° for 12 minutes or until a thermometer inserted in thickest portion of chicken registers 165°.
3. Remove chicken from pan; keep warm. Discard pan drippings (do not wipe pan clean). Add 1 tablespoon oil to pan; swirl to coat. Add potatoes to pan; sprinkle with 1/4 teaspoon salt. Cook potatoes 3 minutes on each side or until browned. Remove potatoes from pan. Add lemon slices to pan; cook 1 minute on each side or until browned. Remove lemon from pan. Add remaining 1 tablespoon oil to pan; swirl to coat. Add carrot, celery, onion, and garlic; cook vegetables for 10 minutes, stirring occasionally. Add wine and chopped fresh oregano; cook 1 minute or until liquid almost evaporates, scraping pan to loosen browned bits.
4. Return potatoes to pan. Combine chicken stock and cornstarch. Add stock mixture, 1/2 teaspoon kosher salt, and 1/4 teaspoon black pepper to pan; bring to a boil. Cook 1 minute. Stir in butter and lemon juice. Return chicken to pan. Sprinkle with parsley.