I had a number of beans in my freezer and used a few of them here. Yes, you can even see some flageolets in there. But when starting from scratch, I usually opt for cannellini. On the bread front, I used a loaf of two-day-old whole wheat bread, but have at times opted for ciabatta. Canned beans can be used here, the equivalent is roughly two 15-ounce cans. Look for cavolo nero - a craggy evergreen-hued kale that might also be labeled lacinato or Tuscan kale.
3 tablespoons extra-virgin olive oil, plus more for drizzling
4 celery stalks, chopped
3 medium cloves garlic, chopped
2 medium carrots or equiv. winter squash, chopped
1 medium red onion, chopped
1 14-ounce / 400 ml can crushed tomatoes
1/2 teaspoon crushed red pepper flakes
1 pound / 16 ounces / 450g cavolo nero (lacinato kale, Tuscan kale), stems trimmed off and leaves well chopped
4 cups / 22 oz / 620g cooked white beans
1/2 pound / 8 oz / 225g crustless loaf of bread
1 1/2+ teaspoons fine grain sea salt
zest of one lemon
lots of well-chopped oily black olives
In your largest thick-bottomed pot over medium heat combine the olive oil, celery, garlic, carrot, and red onion. Cook for 10 -15 minutes sweating the vegetables, but avoid any browning. Stir in the tomatoes and red pepper flakes, and simmer for another 10 minutes or so, long enough for the tomatoes to thicken up a bit. Stir in the cavolo nero, 3 cups of the beans, and 8 cups / 2 liters water. Bring to a boil, reduce the heat, and simmer until the greens are tender, about 15 minutes.
In the meantime, mash or puree the remaining beans with a generous splash of water - until smooth. Tear the bread into bite-sized chunks. Stir both the beans and bread into the soup. Simmer, stirring occasionally, until the bread breaks down and the soup thickens, 20 - 30 minutes. Stir in the salt, taste and add more if needed. Stir in the lemon zest.
Serve immediately, or cool and refrigerate overnight. Serve reheated, or "ribollita" meaning reboiled, the next day ladled into bowls. Finish each serving with a drizzle of olive oil and some chopped olives.
Makes a large pot of soup - enough for 10 servings.