Cut potatoes into large pieces and boil potatoes in 6 cups of water until soft.
Take about 2 cups of potato pieces out and reserve. Chop into smaller pieces to be added later.
Transfer the rest of the potatoes and the liquid to a blender and puree until smooth.
In a large pot, heat oil.
Add onion and sausage and fry until the sausage starts to brown.
Add the garlic and cook for 1 more minute.
Add potato puree and simmer on low heat for 10 minutes, scraping the bottom to get all the caramelized flavors into the soup.
Add kale, salt and pepper. Simmer for another 10 minutes, until kale is softened.
Add reserved chop potatoes and stir to combine.
Add more water as desired, depending how thick or thin as you prefer.