Bring a medium sized saucepan full of water to boil. Cook soba noodles according to package directions. Meanwhile, sprinkle chicken with salt and pepper. Heat oil in large frying pan over medium-high heat. Add chicken, cook 4-5 minutes on each side or until browned. Add plums, honey, mushrooms, broccoli, ginger and garlic. Reduce heat and cook, uncovered, stirring well, for 7 minutes or until chicken is done and plums have turned syrupy. Serve over soba noodles. Sprinkle chopped garlic scapes over top if desired.