Put potatoes in large pan with water to cover sprinkle with salt; cover pan and boil just until tender, about 25 minutes. Drain and cut into bite size into a large bowl.Add remaining salad ingredients to bowl; set aside.
In a double-boiler top; combine oil, flour, mustard,vinegar, sugar ,salt. pepper and paprika.
Cook and stir, over boiling water until thickened.
In a small bowl, slightly beat egg yolk; stir in sour cream. Beat in a small amount of the hot vinegar mixture. Then sit egg yolk mixture into rest of hot liquid; cook stirring, over hot water 3 to 4 minutes, or until slightly thickened. Cool 10 minutes. Now beat egg whites with a rotary beater just until soft peaks form.Still using the beater, beat egg white into cooled dressing until well combined. Refrigerate until ready to use; then add cooled dressing and toss until well combined. Chill for 2 hours.
When potatoes are drained,place the cut-up potatoes in a large bowl and pour the Italian Salad Dressing over potatoes and mix gently. Now,combine all remaining ingredients in a small bowl; mix well. Chill, covered until ready to use. Add to potato salad, toss well and chill for 12 hour.