Heat the olive oil over medium-high heat. Add the onion and garlic and sauté for about 10 minutes, or until very soft and fragrant.
Add the sausage and cook until browned. Drain any excess grease.
Add the smoked paprika and sauté for 1 minute.
Purée 2 cups of the bone broth with 1 can of drained cannellini beans until smooth.
Add the remaining broth to the pot, a little at a time. Add the puréed bean mixture and potatoes. Bring to a simmer over low heat and cook for 10–15 minutes, or until the potatoes are tender.
Add the kale and remaining cannellini beans. Simmer for another 5–10 minutes.
Season with salt, freshly ground black pepper and lemon juice to taste.