*Note: French's yelow mustard will work in this recipe very well. Mix in the egg yolks, mustard, vinegar, & salt together in a bowl. Drop-by-drop beat inh the olive oil until a good, thick maynaise is formed. Add more oil if needed. Beat the egg whites until they are stiff but not dry then fold them into the yolk mixture. Add the sour cream/yogurt to the mixture and stir well. Cover & refrigerate for 2-4 hours.