The bangers and mash with onion gravy was a fine meal. I tried this gravy recipe:

https://www.daringgourmet.com/onion-gravy/

I had not made onion gravy before and used this recipe as a good starting point.

Some slight changes I made was using flour in the beginning instead of cornstarch at the end, as a thickener. I use a bit of brown sugar coupled with brown vinegar to kickstart carmelised onion’s cook time and finally, I ended up purée ing it for a smooth texture.