Traditional British tea fare (not really an appetizer, but there was no category that fit.) Curiously refreshing.
Some cooks slice the cucumers in quarters and take the seeds out. I don't bother.
The filling is really up to you- it is simply a meat pie with a mashed potato top. You can make the potatoes and filling ahead of time, but leave it out to come to room temp before cooking if you do. Otherwise you will wind up burning the top and have a cold middle.