Strip off remaining meat (you don’t need much) sweat onions in a pan, add the bone, just enough water to cover, probably a lamb stock cube, and a good handful of pearl barley, rinsed.
Simmer for a good hour, remove and discard the bone. Leave to cool completely, pref. overnight, skim off any fat.
I cut any fat off the remaining meat, but that’s personal preference. Add meat to heat through thoroughly for the last 5 minutes or so when reheating, but before that, add diced carrots and potatoes - I often add turnip too - IMO it goes very well with this.
Plus usually peas, and S&P according to taste. (Plenty of black pepper here.)
It’s a cold weather favourite in this house - I’ve just put a bone and barley on to simmer.
Can serve spuds separately but I usually chuck them in and serve in big bowls.