Slow Cooker Ribollita With Smoked Mozzarella Toasts

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.