Soak cashews in water overnight. Do this quicker by soaking them for 5 minutes in very hot water, draining it, and soaking them a 2nd time in very hot water (almost boiling).
In a soup pot, add avocado oil, onions, and garlic. Saute over medium heat until onions are translucent, about 5 minutes.
Add vegetable broth and chopped root vegetables (except ginger and dill), and bring to a boil. Allow to boil over medium heat for about 20 minutes, until vegetables are very soft.
In batches, add the broth and vegetables, along with soaked cashews, ginger, and dill. Process until very smooth, then return to pot.
Season the soup with sea salt and pepper.
Garnish soup with creme fraiche, yogurt, or coconut milk, if desired.
Store leftovers in an air tight container refrigerated for up to 5 days, or frozen up to 3 months.