Mix the sour cream with sugar, lemon juice, vinegar, oil, herbs and mustard well, preferably with a whisk in a small bowl. Season to taste with salt and pepper, let it steep for a few minutes so that the salad herbs can release their taste and season again.
If the dressing is too thick, you can either add a splash of vinegar or 1-2 tablespoons of water. We like the dressing best with iceberg lettuce or other somewhat firmer types of salad.
Tip 1: A little garlic granulate or very finely chopped garlic give the dressing the final whistle.
Tip 2: The light version of this dressing is made with creme légère, which instead of 24% fat only has about 16% fat.