Cut the endive salad into very fine strips and wash in plenty of water. Spin the lettuce well in a salad spinner.
Mix the sour cream, 3/4 of the whipped cream and the vinegar in a bowl. Peel the onion and cut into fine cubes. Add to the sauce and season with salt and pepper.
Add the finely chopped endive salad to the dressing and stir well. Also tastes very good with lamb`s lettuce or Lollo Bianco.