Crush the yolks to a paste in a bowl and add a teaspoon of wine vinegar, the mustard, about 1 level teaspoon of salt and a level dessertspoon of black pepper. Beat together thoroughly and then add gradually 6–8 tablespoons of olive oil and 1–2 teaspoons of wine vinegar. Taste to get it as you like it. Finally add the chopped tarragon and pour the dressing over a lettuce salad. If you like, scatter the egg whites, finely chopped, over the lettuce leaves.