Transfer the cashews, water, vinegar, lemon juice, onion powder, garlic powder, and salt to a powerful blender or to a food processor. Blend the mixture on high for 1-2 minutes, or until it's creamy and very smooth.
Taste the dressing. Add freshly ground black pepper to taste and adjust the salt, vinegar, and lemon juice to your liking. Stir in the fresh or dried parsley and dill and the chives, if using. Serve or store in an airtight container in the fridge for up to 4 days.