Peel the skin off the mackerel and discard. Add to a food processor. Add the rest of the ingredients (apart from the celery and bread) and whizz until you get a nice creamy pâté. Plate up into a serving bowl.
Serve with the celery and some fresh bread. You can also griddle your bread to make toasts.
Recipe by A Modern Rose at http://www.amodernrose.com/smoked-mackerel-pate/