Combine all the ingredients in a large bowl.
Stir well with a large spoon or rubber spatula to mix.
Cover and refrigerate for 1 hour before serving, or keep refrigerated for up to 1 day.
Yield: 2 1/2 cups
1 cup shredded green cabbage
1 cup shredded red cabbage
1/4 cup minced yellow onion
1/4 cup mayonnaise
2 tablespoons finely chopped green onion (tops only)
1 tablespoon Creole mustard or other whole-grain spicy mustard