In a heavy soup pot (I use a Dutch oven), sautée the onions and sausage together with olive oil until the onions are translucent and the sausage is almost cooked through. Add the potatoes and water or chicken broth. Bring to a boil. When the potatoes are almost done, season the broth with salt and pepper to taste, then add the kale. Cover and simmer for another 5-10 minutes, until the kale is softened to your liking. Ladle into bowls and drizzle with olive oil.