Bangers and mash with onion gravy is a classic british dish and you can ring the changes by jazzing up the gravy with the addition of a little mustard. Wholegrain mustard is the preferred choice as it also adds some texture to the gravy. You can, however, also use english mustard as this will add a real punch of flavor. As well as sausages, thick onion and mustard gravy is also the perfect sauce for many meat dishes including roast meats or poured into a yorkshire pudding. The gravy is straightforward and quick to make and as it freezes well make lots.