your choice of vinegar
In a blender, combine walnuts, walnut oil and a splash of your favorite vinegar. Pulse until thick and creamy. Taste, and add more vinegar or oil to get to your desired level of tanginess or creaminess. Add water if you'd like to thin the sauce to make a dressing. Add fresh or frozen herbs, if you'd like, and blend until smooth.
I divided the sauce in half, leaving the first half as is (walnuts + walnut oil + a splash of both champagne vinegar and sherry vinegar). Then I added a fresh batch of cilantro to the second half. I just stored them in their thick glory in the fridge. Then during the week, I used them a bunch of different ways, in addition to thinning them and using them as salad dressings:
The plain walnut one was the dressing in a batch of roasted beet & barley salad...
The walnut-cilantro one was smothered over a piece of sea bass for dinner one night...