Cut the eggs in half and remove the yolks.
Place the egg yolks and butter in a bowl and mix together until smooth.
Finely dice the egg whites. Wash the pepper, remove the seeds and dice the flesh finely, together with the onion.
Stir the diced egg white, pepper and onion into the butter and egg yolk mixture.
Season with salt, celery salt, pepper, curry powder and cayenne.