In a high-speed blender, add the cashews, dill, water, olive oil, lemon, miso or soy sauce, salt and pepper. Blend on high until totally smooth. If the sauce is super thick, thin it out with some water or more lemon (if it needs more acid). You want it to be runny, not gloppy (it will thicken as in cools in the fridge). Taste and season with salt or lemon, if needed.