MarthaStewart.com has a good tip on using the last of your mustard to create a Dijon vinaigrette with the last bit of mustard in your jar. The mustard is used as an emulsifier to help keep everything in suspension (specifically the olive oil and balsamic vinegar) and prevent separation.
No-Waste Dressing Have a tiny bit of mustard left in the jar? Toss in a few ingredients, and shake a tangy Dijon vinaigrette right in the container. A crushed garlic clove, some chopped fresh herbs and minced shallot will add the right flavor. Pour in balsamic vinegar, season with salt and pepper, then close the lid and shake. Add olive oil; shake again to emulsify the dressing, and then drizzle over your favorite salad. With a tightly sealed lid, it will keep in the refrigerator for up to one week.
