Balsamic Salad Dressing???????

Does anyone know of a good recipe for a balsamic vinegar salad dressing? I am thinking along the lines of balsamic vinegar, wholegrain mustard, oil substitute????? Just have a notion for a really nice salad with a balsamic dressing...... don't like the shop bought varieties........ have tried them and I prefer the homemade variety but need to find a way round the oil.