Heat a medium non-stick frying pan. Add onions, garlic, celery and 1-2 tbsp of water. Saute these veggies on high heat for 2-3 minutes or until onions become translucent.
Transfer sauteed veggies into a large pot. Add cauliflower florets, cashews and vegetable broth. Bring the contents to boil, then turn the heat down to medium and let your soup simmer for about 15-20 minutes or until cauliflower is nice and soft.
Transfer your soup into a blender (or use an impact blender), add apple cider vinegar and blitz for 2-3 minutes, making sure the mixture is nice and smooth. Top with your preferred toppings and enjoy!