Three-fish Layered Terrine with Avocado Sauce

Terrines always seem to be an awful lot of work, but really they are not; they can be made a couple of days in advance and always cater for a lot of people – ideal for that family gathering. Not to worry if you have too much, they do keep very well in a refrigerator. However, do remember to leave them at room temperature for at least 1 hour before eating as, if served straight from the refrigerator, they will be too cold and therefore lose their flavour, which is often delicate.