Boil about six pieces of celery root. When soft, peel and mash. Season with salt, pepper, a little onion powder, a teaspoon of home-made mustard and plenty of mayonnaise. Shape into pyramids, put mayonnaise on the top of the pyramid, and on top of that either a little well-seasoned caviar or some sardellen butter shaped in a pastry bag. Serve on a slice of beets and a lettuce leaf.