Why It Works
- Sautéing the vegetables in oil coaxes out their flavor to make a more delicious broth.
- Using a pressure cooker allows us to cook dried beans from start to finish in just one hour.
- Contrary to popular belief, adding salt to the water when cooking beans improves their consistency.
- Adding the kale later in the cooking process ensures it retains some of its texture and doesn't turn to mush.
The history of ribollita is one of tradition—after making a big pot of vegetable soup, Italians would stretch any leftovers into a stew by reheating it the following day and adding beans and stale bread to the mix, thereby creating a new meal for a new day. That's why it's called ribollita, which means "re-boiled," a name that describes the two-stage cooking process.
But while ribollita may have been born out of frugal necessity, there's no reason we need to follow that same path today. Using a pressure cooker, we can make the soup all at once in a fraction of the original's stovetop cooking time. It's such a huge time-saver, and leads to such great results, that I'm not sure I'll ever want to make ribollita without a pressure cooker again.
A pressure cooker is the perfect tool for cooking this dish for a few reasons. First, ribollita is at its best when all the vegetables are cooked to a texture that borders on melting. And because a pressure cooker is able to cook food at a higher temperature than what's possible in a normal simmering pot, it can deliver those exceptionally tender vegetable morsels in much less time.
As effective as a pressure cooker is at tenderizing vegetables, it's even more so with the beans in ribollita. Dried beans, which deliver far better flavor than their canned counterparts, normally take many hours to prepare. First, there's the overnight soaking time (this can sometimes be skipped, though there's a slightly higher risk of the beans cooking more unevenly if you do), followed by a long and gentle simmer that can take well over an hour in the case of the cannellini beans here.
With a pressure cooker, though, you can skip the soaking step, dump the dried beans straight into the cooker, and end up with creamy, tender beans just one hour later. Because ribollita is all about making the ingredients meld together into a stew, it's totally fine if some of the beans overcook or blow out—the ribollita will be that much more delicious.
The two thing we keep out of the pressure cooker until later in the process are the kale, which turns to muddy mush if allowed to cook under high pressure for a full hour as well as the bread, which only needs a few minutes to absorb the broth and soften (note too that while ribollita traditionally used up stale bread remnants, you can use fresh bread instead and get equally delicious results).
Keep in mind that while this recipe is formulated to fill a six-quart pressure cooker, you are free to make any substitutions you want, adding or replacing any vegetables or even the bean type based on your personal preferences or what ingredients you have at home. The only things you'll need to pay mind to are that you don't accidentally overfill your cooker when making substitutions and that different beans cook at different rates, so you may need to adjust your cooking time accordingly.
- 3 tablespoons (45ml) extra-virgin olive oil, plus more for drizzling
- 4 large carrots (1 1/4 pounds; 525g), peeled and cut into 1/4-inch dice
- 3 large celery stalks (8 ounces; 240g), cut into 1/4-inch dice
- 1 large (13-ounce; 370g) leek, white and light green parts only, cut into 1/4-inch dice
- 1 medium (7-ounce; 200g) red onion, cut into 1/4-inch dice
- 2 1/2 cups peeled, seeded, and diced butternut squash (12 ounces; 360g; about 1/2 of a medium squash)
- 3 medium garlic cloves, thinly sliced
- Kosher salt
- 8 ounces (1 1/2 cups; 225g) dried cannellini beans
- 2 sprigs fresh thyme and/or sage
- 1 bunch (about 8 ounces; 225g) lacinato kale (a.k.a. dinosaur, Tuscan, or black kale), stemmed, leaves roughly chopped
- 4 ounces (110g) fresh or stale rustic crusty bread, cut into 1-inch cubes
- Freshly ground black pepper
- Freshly grated Parmigiano-Reggiano, for serving (optional)
In a 6-quart stovetop pressure cooker set over medium-high heat or an electric multi-cooker (such as an Instant Pot) set to sauté mode, heat olive oil until shimmering. Add carrots, celery, leek, onion, squash, and garlic, season with salt, and cook, stirring frequently, until softened but not browned, about 20 minutes; lower heat if necessary to prevent browning.
Add dried beans along with enough cold water to reach the pressure cooker's maximum fill line; this will vary slightly by pressure cook model but should be about 2 1/2 quarts (2.3 liters), enough to cover the vegetables and beans by roughly 2 inches (5cm). Add thyme and/or sage. Season well with salt.
Seal cooker and bring to high pressure over medium-high heat, if using a stovetop model, or by switching to pressure-cooker mode on an electric multi-cooker. Cook at high pressure for 1 hour.
Rapidly release pressure on the cooker (how you do this will vary depending on the model; see manufacturer's instructions). Open lid, being careful to avoid the strong blast of steam. Check beans; they should be creamy throughout. If they're still firm, return cooker to high pressure and cook 10 to 15 minutes longer, then check again. (For this recipe, it's far better to overcook your beans than undercook them.)
Stir in kale, then either simmer uncovered for 20 minutes until tender or replace lid and return to high pressure for 15 minutes if you want the kale very well done before rapidly releasing and opening the cooker again.
Stir in bread and simmer until it melts into the soup and no firm or distinct pieces remain, 10 to 15 minutes. Season with salt to taste; discard thyme/sage sprigs. You can adjust the consistency of the ribollita by either adding more water (or vegetable stock) if it's too thick, or simmering it to reduce the liquid until it reaches your desired thickness level; this is entirely a matter of personal preference.
Divide ribollita between individual serving bowls. Drizzle with fresh olive oil and top with freshly ground black pepper and grated cheese, if desired. Serve.
Make-Ahead and Storage
The ribollita can be refrigerated for up to 5 days or frozen for up to 3 months. You may need to loosen with a little extra water when reheating.