We like to make our own salad dressing. We take regular salad dressing, vinegar, and soy sauce and add some artificial sweetener and mix them all together (pretty much a one to one proportion).
In essence, we are diluting out the calories in the regular dressing. There is no magic formula to do doing this. You just have to play around with it until you get it the way you want it to be. You can even add in a little BBQ sauce for an even sweeter flavor.
It is an exclusive item on the Williams-Sonoma website.