Turmeric adds a pungent flavor and a deep yellow color. It can be found in the spice section of your grocery store.
Microwave first 7 ingredients in a 1-quart glass bowl at HIGH 3 to 4 minutes or until thoroughly heated, stirring once. Let cool.
Combine cabbage, bell pepper, pimiento, and, if desired, onion in a bowl. Drizzle with dressing, tossing to coat. Cover and chill at least 8 hours or up to 3 days.