"To come up with this dish, I used a number of different recipes plus some ideas of my own. It's great for potluck because it's made the night before and the flavor keeps getting better. Whenever I serve it I'm inundated with recipe requests."
Mix cabbage, onion, green bell pepper, red bell pepper, carrots, and olives together in a large bowl.
Whisk vinegar, oil, sugar, Dijon mustard, salt, celery seed, and mustard seed together in a saucepan. Bring to a boil; cook and stir until sugar is dissolved, about 1 minute. Pour hot dressing over cabbage mixture and toss gently. Cover the bowl with plastic wrap and refrigerate for at least 8 hours or overnight.