I checked Jacques Pepin's newest cook book out the library. I have made this salad dressing a couple of times and it is a winner. It is tart so if you want a sweeter dressing add a little honey. I like it both ways depending what is in the salad.
2 T mayonnaise
2 T Dijon-style mustard
2 T water
1 T cider vinegar
1/4 t salt
1/2 t freshly ground black pepper
1/2 cup extra-virgin olive oil
Put the mayo, mustard, water, vinegar, salt and pepper in a jar. Add half the oil, cover tightly with a like and shake well to emulsify the ingredients. Add the rest of the oil, replace the lid, and shake until the mixture is smooth and creamy. The dressing can be refrigerated for several weeks.