In a large pot or Dutch oven, cook/saute your onion, garlic, and celery in olive oil for just a couple minutes, until your onions are softened.
Add your potatoes to the pot along with 7 1/2 cups of water. Allow to simmer for 10-12 minutes (or more, if you've cut your potatoes bigger than 1/2 inch cubes) or until potatoes are fork tender. Once potatoes are tender, or nearly so, add your corn.
In a high-speed blender (I use Vitamix.), place 1 1/2 cups water, 1 cup raw cashews, McKay's seasoning, celery seed, and salt. Blend on high until the mixture is nice and smooth. Add blended cashew mixture to your pot and stir until everything is well-incorporated.
Now, you can eat the soup as is, and it will be delicious. I like to make it just a little more creamy by blending about 3-4 cups of the soup (potatoes, corn, onion, and all) in a high-speed blender until smooth. Then, I pour it back into the pot, and presto! It's nice, thick, and creamy.
Serve soup hot with your favorite vegan crackers, chips, or croutons. Enjoy!