In a large bowl, combine the cabbage, pimientos, green pepper and onion. Toss lightly; set aside. Combine remaining ingredients in a medium saucepan; bring to a boil. Reduce heat; simmer, uncovered for 20-25 minutes or until slightly thickened. Pour over cabbage mixture. cover and regrigerate 4 hours or overnight. Slaw will keep in the refrigerator for several days.