Mustard is one of those fridge-door features that essentially becomes a part of the landscape: It almost feels like the jar will never, ever run out, like there might be some secret mustard spring very gradually replenishing it.
When you finally have just a modest slick of it left on the walls of the jar (or if you're just trying to hit the bottom), don't let it go to waste. Even a little bit of mustard provides round, spicy punchiness to whatever it's added to. Here are a few ideas for how to use it:
Make a vinaigrette directly in the mustard jar: Drizzle in oil, salt and pepper, a bit of honey, and shake like the Dickens—then pour over your salad.