Shouldn't I pre-soak the cashews? I eat unsoaked nuts all the time and in this recipe, they cream up beautifully without prior softening. That said, if you find it helpful to your digestion, you can certainly soak the cashews prior to blending.
Umami: the term umami is typically used to describe a savory taste/flavor.
Umami seasoning: you can purchase umami seasoning in stores and online - I use the one from Mushroom & Company (Trader Joe's). It contains: 2 varieties of mushroom powder; thyme, black pepper, mustard seed and salt. Other umami powders are mostly a mix of mushroom powder and salt.
Sodium Level: umami seasoning/powder is salty so if you choose to skip the seasoning (which I don't recommend because it's super tasty) you may wish to add more salt to taste. Similarly, if you are using the umami seasoning, go easy on the added salt and be sure to taste before adding more.