Wash the iceberg lettuce and cut into strips. Chop the onion into small pieces.
Mix the balsamic vinegar, sunflower oil, herbal salt, onions, honey, mustard, crème fraîche and season to taste. It should strike the right balance between sweet and salty. Then you can dilute the vinaigrette with a little water if you like.
For a mixed salad, i.e. with tomatoes and cucumbers, I would not add any more water because they contain enough water.