Great ideas with stock. Alas, I don’t have enough leftovers for it as I tend to use everything (and for meat, I’m weird and don’t like bones or anything, so it’s always ground or filet. Only sometimes when beef shanks are on sale I eat leftovers and cook them for my wife, but that doesn’t leave many bones)
edits:
And finishing a dish with some sesame oil can add a really good flavor
Toasted sesame oil. I use it on pretty much anything somewhat Asian :D