Dice the celery, chop up the hard-boiled egg and get the rest of the ingredients nearby.
Open the can of tuna and squeeze out the excess water.
In a medium sized mixing bowl, add the tuna and break it up some. Not too much though. The chunks look nice when serving however the more you break it up the further it will go.
Add the celery, egg, dill, relish, mustard and a little bit of mayonnaise. Mix it together with a fork being careful not to overwork it. Depending how you like it or if you are on a diet or not, adjust the amount of mayonnaise.