In culinary terms, most people will think of apply jelly, juice, compote, pie, cake and crumble. Oh yes, and cider.
Allow me to to point out that apples make the perfect partner with oily fish.
A salad of pickled herring with red onions, fennel, dill, apple and soured cream is a delight. Kippers (Smoked herring) or smoked mackerel go well with apples, pink grapefruit, fennel, soft-boiled quail eggs and a spoon of mayonnaise or salad cream. A poached mackerel combines well with a sharp grated apple and a little soured cream.
Coming to think of it, I think the humble apple is one of the most versatile home-grown cooking ingredients we have available, probably ranking second right after the egg.