In a large pot, add a splash of water and your onions, celery and potatoes. Cook for 5 minutes until soften. Add garlic and saute for another minute.
Add in the remaining ingredients except the hearts of palm and slurry. Continue to cook until potatoes are tender. Add the cashew cream and chopped hearts of palm.
If you want a thicker soup, you can add the slurry and cook for another 3 minutes.