2 egg whites
1/2 cup seasoned rice vinegar
1/2 cup peach preserves
1 T garlic, minced
1 T whole grain or dijon mustard
1/4 cup sour cream, non-fat works OK
juice of one lemon

Place the above ingredients in a blender or food processor and blend.  
While blending, add olive oil in a steady stream, a little at a time, 
until dressing is thickened.  
Season with salt and pepper.