Remove the meat and skin from the chicken. Discard the skin and bones. Finely chop the meat and place it in a bowl with the celery, mayonnaise and mustard. Season and mix to combine.
Spread the chicken mixture over the bread. Sandwich 1 slice together with another slice of bread, remove the crusts and cut the sandwiches into fingers.
Tip: The filling can be made ahead and refrigerated for up to 1 day. You can also toss the filling through hot pasta with a little grated Parmesan.
This tutorial is excerpted with permission from <a href="http://amzn.to/1ldAqpj">"Grow Harvest Cook: 280 Recipes from the Ground Up"</a> by authors Meredith Kirton and Mandy Sinclair, photographer Sue Stubbs, designer Susan Cadzow, and published by Hardie Grant Books.