Step 1

Heat the olive oil in a large soup pot over medium heat. Add the leek, chopped carrot and fennel and season with 1/2 teaspoon salt and the pepper flakes. Saute slowly until the vegetables are very soft but not browned, about 3 minutes.

Step 2

Add the white beans and farro and toast for a minute or two, then add the tomatoes with their juices and the chicken stock, thyme, parmesan rind and 4 cups water. Bring to a boil, then reduce the heat to a steady simmer. Cook, stirring occasionally, about 1 1/2 hours, or until the beans are tender but not mushy; they should be firm and separate. Season with salt.

Step 3

Add the kielbasa, kale and sliced carrot. Cook until the kale and carrot are tender, about 15 minutes. Remove and discard the thyme sprigs and parmesan rind. Serve with a drizzle of olive oil, a sprinkle of grated parmesan and a squeeze of lemon, if you like.