Preheat your oven to 350 degrees F. Take the walnuts and spread them on a baking sheet. Bake these until lightly toasted, probably about 5 - 7 minutes. Let them cool before coarsely chopping.

To make the dressing, whisk the vinegar, mustard, sugar, 1 1/2 teaspoons of salt and 1/2 teaspoon of pepper into a large bowl. Then, gradually whisk in the olive oil. then do the same with the sour cream.

Add your cabbage, cilantro, dill, tarragon, scallions, grapes, and walnuts to the bowl. Toss to coat all of it with the dressing, then let it refrigerate for 1 - 4 hours before serving.