Known as ribollita in Italian, this soup is a mainstay of Tuscan cuisine. It's hearty and full of healthy ingredients, so if you like bean soup, we think you'll find this version very satisfying.
The classic ribollita is based on borlotti beans, which in the US we know as cranberry beans. You can also substitute cannellini, pinto or white navy beans. Some of the beans are puréed to add flavor and creaminess.
Traditionally, stale bread is added to ribollita, but we prefer a lighter dish. For a similar effect, you can garnish the soup with a drizzle of olive oil, a sprinkle of croutons and ribbons of Parmesan cheese, if you like.
Heat the olive oil in a large pot over medium-high heat; when the oil is hot, add the carrots, celery, onion, parsley and garlic. Cook, stirring frequently, until the vegetables have softened and begun to brown lightly, about 15 minutes. Season with salt and pepper to taste.
Add the tomatoes, kale, chicken broth and 8 cups of water to the pot. Raise the heat to high and bring the soup to a boil. Reduce heat, cover the pot, and cook at a simmer for 5 minutes. Add 2 cups of the beans to the pot and cook, covered, until warmed through (or if you're using fresh kale, unitl the kale is tender, 10 to 15 minutes).
Meanwhile, place the remaining cup of beans in a food processor and purée with 1/4 cup of warm water. Add the purée to the soup and season with salt and pepper to taste.
To serve, divide among warm bowls and drizzle each serving with some of the olive oil. Garnish with croutons and shaved Parmesan, if desired.