Cabbage Salad Dressing

Add celery seed to vinegar. Bring to a boil and cool. Combine remaining ingredients and beat well while vinegar mixture is cooling. This can be put in the blender. When I do it by hand with a spoon it is rather a slow process as I have to keep adding a small amount of oil at a time in order to get the oil blended with the onion, sugar, salt and mustard. Then I add the vinegar and celery seed which has been brought to a boil and cooled. I stor