Slow Cooker Ribollita With Smoked Mozzarella Toasts
This classic Italian vegetable soup is a wonderful way to use up stale bread and leftover vegetables — and can be prepared in a pot, in a pressure cooker, or in a slow cooker. With the exception of sliced sandwich bread (which is too flimsy), any crusty bread will work here: sourdough, ciabatta, multigrain and so on. (Since you’re toasting it, it’s not necessary for the bread to be stale, but it certainly can be.) The olive-oil-rich sautéed vegetables melt into the soup as it simmers, but you can throw in other leftover cooked vegetables at the end, with the greens.
- Total:
- Serves: 6 persons
Ingredients
- ¼cup olive oil, plus more for drizzling
- 1large yellow or red onion, finely chopped
- Kosher salt and black pepper
- 1large leek, trimmed, white and light green parts sliced
- 3celery stalks, finely chopped
- 1small fennel bulb, bulb cored and finely chopped, fronds reserved
- 14garlic cloves, smashed and roughly chopped
- 2dried bay leaves
- 1teaspoon red-pepper flakes, plus more for serving
- 1cup dry white wine
- 5cups chicken or vegetable stock
- 1 ½cups dried white beans, such as cannellini or great Northern (no need to soak)
- 1(15-ounce) can crushed tomatoes
- 3fresh thyme sprigs or 1 teaspoon dried thyme
- 1fresh rosemary sprig or 1/2 teaspoon dried rosemary
- 2tablespoons fresh lemon juice (from about 1/2 lemon)
- 1bunch kale, chard or collards (about 12 ounces), stemmed and finely chopped, or 1 (10-ounce) bag frozen chopped spinach or kale
- 2teaspoons balsamic vinegar, preferably aged
- 8thick slices crusty bread
- 1garlic clove, cut in half
- Olive oil
- 8ounces smoked or regular mozzarella, cut into 8 (1/4-inch-thick) slices
Instructions
Step 1
Heat the oil in a large Dutch oven or skillet over medium. Add the onion, season with salt, and cook, stirring occasionally, until limp and translucent, 6 to 8 minutes. Add the leek, celery and fennel, season with salt, and cook, stirring occasionally, until softened and fragrant, about 8 minutes. Add the chopped garlic, bay leaves, red-pepper flakes and white wine; season generously with black pepper. Stir well and let the wine come to a simmer before turning off the heat.Step 2
Scrape the mixture into a 6- to 8-quart slow cooker. Add the stock, beans, tomatoes, thyme, rosemary and lemon juice. Cook until the beans are tender and creamy, about 6 hours on high or 12 hours on low.Step 3
Before serving, remove and discard the bay leaves and herb sprigs. Switch the slow cooker to high (if it’s not already), and stir in the greens and vinegar.Step 4
Let the greens cook while you make the toasts: Turn on your broiler. Rub the bread slices with the halved garlic and drizzle them with olive oil. Position a rack 6 inches from the broiler, then toast sliced bread under the broiler until very light golden, 1 to 2 minutes. Add 1 slice of mozzarella to each toast and broil until softened and browned in spots. Taste the soup and season to taste with salt and pepper.Step 5
Divide the soup among bowls and add a mozzarella toast to each bowl. Garnish with the reserved fennel fronds, and additional black pepper or red-pepper flakes, if desired.