1. Place onion and potatoes in water and bring to a boil. Reduce heat and simmer until potatoes are cooked.
2. Add corn and stock, and return to a boil. Meanwhile, blend cashews with 1 cup of water in a blender, until smooth and creamy. When soup comes to a boil, add cashew mix. Rinse blender with a little water and add this to the soup.
3. Reduce heat to simmer for a few minutes until heated through. Garnish with parsley or scallions.