Toss cabbage, carrot, onion and jalapeno pepper with salt. Let sit in a colander at least 1 hour to allow water to drain. Rinse off salt, then spin dry in a salad spinner. Transfer vegetables to a large bowl.
In a saucepan, combine sugar, sour cream, mayonnaise, mustard, chili sauce, vinegar and celery seed. Whisk constantly until it comes to a boil, then pour over cabbage. Toss well to coat vegetables with sauce. Cover with plastic wrap and refrigerate at least 1 hour before serving.