cool as a cucumber sandwich on a rainy day
This is the sort of thing you don't really need a recipe for - in the manner of toast or eggs or many other of those intuitive, sort of obvious things - it is more of an exercise in assembly. I have found though, after many a cucumber sandwich, that a good level of buttering, salt and pepper and a zingy mayonnaise add very much to the enjoyment of the essential ingredients: bread and cucumber. Crusts on or off is really up to you. I cut them off but ate them anyway because white bread is such a rare childhood-esque indulgence that I didn't want to waste any crumbs.