Grind onion, carrots and celery in a food processor. Put into a large mixing bowl
Add the box of potato pancake mix, eggs and oil. Mix well and spoon onto foil to form two to three rolls, approximately 2 inches in diameter by 8 inches long
Wrap and pinch the ends of the foil closed. Bake at 350 degrees F for 1 hour
Remove from the oven and let stand about 10 minutes. Unwrap foil and slice into pieces to serve.
