Combine first 5 ingredients in a zip-top plastic bag, and add chicken. Seal and shake to coat. Remove the chicken from bag, shaking off excess flour. Heat oil in a large skillet over medium-high heat. Add chicken, and cook 3 minutes on each side or until lightly browned. Remove chicken from pan; keep warm. Add onions to pan, and sauté for 2 minutes. Add onions to chicken, and keep warm. Add plums and 1/4 cup wine to pan, scraping pan to loosen browned bits; cook 4 minutes or until plums are browned. Add 1/2 cup wine and ginger to pan; bring to a boil. Add the chicken mixture to pan, and bring to a boil. Reduce heat, and simmer 5 minutes or until chicken is done.