Sprinkle meat with seasonings. Place onions, carrots and celery in crockpot. Top with meat and add bay leaf, vinegar, and water. Cover pot and cook on low for 5 to 7 hours. Remove meat; turn to high. Add cabbage; cover and cook on high for 15 to 20 minutes or until cabbage is done.

Meanwhile melt butter in saucepan. Stir in instant onion and flour. Drain 1.5 cups broth from crockpot. Pour broth, horseradish and salt into saucepan. Cook over low heat, stirring constantly, until thickened.

NOTE: when adding cabbage, wait until crockpot reaches the high temperature. This may take a few minutes since the cover has been removed and much heat has been lost.