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Regular readers of this blog will know that lentils are my favorite legume. I adored my grandmother Angelina’s pasta and lentils as a kid, and I still love just about anything made with lentils, including of course soup.
Lentil soup or lentil soup is a winter standby in Italian home cookery, but lentil and leek soup is unusual in that it doesn’t start with the typical sautéed (flavor base) of onion, garlic or the ‘holy trinity’ of onions, carrots and celery. Instead, this soup features leeks, another classic winter vegetable, which lends the savor of other alliums along with its uniquely sweet and delicate taste.
Leeks aren’t the most typical of Italian vegetables, but leek dishes do show up in Italian cookery, in particular in Tuscan cookery as in the lovely leek cake (a leek tart) and leek soup (leek soup), though the renowned leeks from Cervere from nearby Piedmont region take the prize for the best leeks in the peninsula.
And the leeks here aren’t merely a flavor base. They’re a co-equal partner. Both lentils and leeks are cooked separately, then simmered together just long enough for their flavors to meld, ensuring that each retains its own individual character. It’s a “marriage” made in heaven. The sweet, delicate taste of the leeks provides a delicious contrast and complement to the earthiness of the lentils.
And not only that: lentil and leek soup it is an easy soup, and fairly quickly put together. Although the recipe involves a few steps, the actual active cooking time is perhaps 30 minutes top, making it a fine choice for a warming weeknight supper.
Ingredients
Serves 4-6
- 400 g (14 oz) lentils
- 1-2 cloves of garlic, slightly crushed and peeled
- A spring of fresh parsley
- Salt, to taste
For the soup:
- 100g (3-1/2 oz) bacon, diced*
- 4-5 small to medium sized leeks
- Broth, preferably homemade meat* or vegetable broth, or water, if needed
- Olive oil
- Salt and pepper
- A sprig of fresh rosemary (optional)
Optional toppings:
- Freshly grated parmgiano-reggiano, to taste*
- Olive oil
* Omit these ingredients for a vegetarian/vegan dish
Directions
Prep and cook the lentils
Optionally, set the lentils in a large bowl covered with water by at least 8cm (3 in). Soak overnight (or at least two hours).
In a large pot, place the lentils, along with the garlic and parsley. Cover with water by at least 3cm (1 in). Simmer until barely tender. (Cooking times vary wildly depending on variety of the lentils and whether they’re pre-soaked. See Notes below for details.) Add water as needed to keep the lentils covered. When they’re done, turn off the heat, add salt to taste and let rest for at least 5 minutes. Pick out and remove the garlic and parsley.
Prep and cook the leeks
Meanwhile, prep the leeks by trimming off their dark green tops, then cut them down the middle lengthwise, and if thick again into quarters. If you see any grit, then rinse the leeks thoroughly, drain them and let them dry. Cut the leeks horizontally into large dice.
In a large saucepan, saucier or braiser, sauté the diced pancetta in olive oil over gentle heat until it’s rendered its fat and just begun to brown. Then add the diced leeks and a small pinch of salt and simmer until they are quite soft and well reduced, usually around 15-20 minutes. Add a few drops of water from time to time to help the leeks along and prevent them from browning.
Putting the soup together
When the leeks are very tender, add the lentils, drained of their cooking water, to the pot. Stir the lentils into the leeks and let them simmer together for 5 minutes or so, turning from time to time.
Add enough broth or water (or the cooking liquid from the lentils) to the pot to cover the lentils and leeks entirely, along with the rosemary if using. Simmer everything together for another 5-10 minutes or so.
If you like a thicker soup (and I often do) crush some of the lentils with a wooden spoon or spatula against the side of the pot as they simmer, as many as you need to get the consistency you prefer. Conversely, if the soup is too thick for your taste, add more liquid. At the end of cooking, taste and adjust for seasoning.
Serve hot, topped if you like with a drizzle of olive oil or a dusting of freshly grated parmigiano-reggianoor both.

Notes
You can make lentil and leek soup with any kind of lentil, but generally speaking you want brown or green lentils. In Italy the lentils of choice are the small green Castelluccio lentils from the Umbria region. They have very tender skins so will be perfectly tender after 30-40 minutes of cooking without pre-soaking. They are hard to find here in the US, though they are sometimes available online. You can find other lentils imported from Italy, usually from Umbria like these from gustatory.com easily, but not for whatever reason the famous ones from Castelluccio. Go figure… That said, the excellent Le Puy lentils are much easier to source and work perfectly in this soup. And honestly, any good quality lentils will do fine. Since this is a soup, they don’t even need to hold their shape, though I still prefer it if they do.
Cooking times for lentils can vary enormously. Generally speaking, lentils take a lot less time to cook than they used to. The green lentils I used for this soup took only 15 minutes after an overnight soak. Unsoaked lentils usually take anywhere from 25 to 45 minutes, depending on the variety and how old they are, although some can take as much as 60 minutes should do. So check the package to be sure. And test their doneness after 15 or 20 minutes to get a sense of how fast they’re cooking.
To soak or not to soak?
Many varieties of lentils these days don’t need soaking, especially if they’re smaller and tender-skinned like Castelluccios or Le Puys. That said, I still soak lentils if I have the time and foresight. Since they’re quicker to cook, I find pre-soaked lentils hold their shape better. And they just plain have finer taste and texture. Pre-soaked lentils are less likely to cause gas, if that’s a problem for you, and some sources like this one and this one—especially out of India where, of course, lentils are a staple—say they’re more nutritious as well.
An overnight soak is ideal for most legumes, but for lentils even two hours will do some good. You can also “speed soak” lentils and other legumes by bringing to a boil, then turn off the heat and covering them. Let me stay for about 30 minutes for lentils, an hour for most other legumes. That said, if you’ve forgotten to soak, or just don’t want to bother, you can just go ahead and simmer your lentils for a bit longer.
Choosing and prepping your leeks
As for the leeks, as mentioned at the top, the famed Cervere leeks would be your top choice. They are especially sleek and tender, with an exquisitely sweet and delicate taste. Outside Italy, just look for the best looking leeks you can find. The size of leeks can vary enormously. For me, I prefer to use smallest, slimmer leeks if I can find. They are more tender and, to my mind, have a finer flavor. But here again, use what you can find. As the old saying goes, don’t let the best be the enemy of the good.
Leeks these days are often sold with little or no grit, but do check and if you see the slightest trace of grit, rinse them well. It’s always better to be safe than sorry.
The dark green tops aren’t used in the dish, but no need to throw them away. Add them to your next batch of broth. They lend wonderful flavour.
Variations
As mentioned at the top, this is a fairly unusual recipe for lentil soup. More typical of Italian lentil soup recipes is a flavor base of onion, or onion and garlic, or the usual “holy trinity” of onion, carrot and celery. Sometimes, especially in southern Italian recipes, a tomato or two goes into the post as well. And the estimable Jeanne Caròla Francesconi has a very simple recipe for a Neapolitan style lentil soup where you boil lentils until tender in a large pot, adding a garlic clove, a few chopped tomatoes, olive oil and a dash of salt directly to the pot along the way.
Otherwise, the recipe for lentil and leek soup provides lots of room for variations. If you want to veganize the recipe, just omit the bacon and use vegetable broth or water. If you want to lean into the alliums, you can add a sliced onion or garlic to simmer along with the leeks. Instead of rosemary, sage would work nicely.
Or you can mix things up by adding a few potatoes or some winter squash, peeled and diced, or some mushrooms, thinly sliced and sautéed in garlic and oil, to the final simmer. Or a few tomatoes to simmer along with the leeks for color.
As for toppings, in addition to the classic ones mentioned in the recipe above, bread croutons (fried or air fried in olive oil) would be lovely for an even more stick to the ribs dish. Or a grinding of black pepper to add some spice.
If you want to save yourself cleaning an extra pot, you can always add uncooked lentils (in this case, preferably pre-soaked) directly to the leeks, then simmer everything together until the lentils are tender. This works perfectly fine but the longer cooking time means that the leeks do tend to “disappear” into the soup. They will still lend their lovely flavor but lose their individuality.
Making ahead
It scarcely needs saying, but this soup can be made ahead with excellent results. In fact, like a lot of legume dishes, I find it’s even keyboard if it’s had an overnight rest.
Lentil and leek soup
Lentil and Leek Soup
Course: First
Cuisine: Italian
Keywords: soup, vegan, vegetarian
- 400g 14 oz lentils preferably brown or green
- 1-2 cloves garlic slightly crushed and peeled
- A spring of fresh parsley
- Salt to taste
For the soup
- 100g 3-1/2 oz bacon said
- 4-5 small to medium sized leeks
- Broth, preferably homemade meat or vegetable broth, or water, if needed
- Olive oil
- Salt and pepper
- A spring of fresh rosemary optional
Optional toppings
- Freshly grated Parmigiano-Reggiano
- Olive oil
Prep and cook the lentils
Prep and cook the leeks
Meanwhile, prep the leeks by trimming off their dark green tops, then cut them down the middle lengthwise, and if thick again into quarters. If you see any grit, then rinse the leeks thoroughly, drain them and let them dry. Cut the leeks horizontally into large dice.
- In a large saucepan, saucier or braiser, sauté the diced pancetta in olive oil over gentle heat until it’s rendered its fat and just begun to brown. Then add the diced leeks and a small pinch of salt and simmer until they are quite soft and well reduced, usually around 15-20 minutes. Add a few drops of water from time to time to help the leeks along and prevent them from browning.
Putting the soup together
When the leeks are very tender, add the lentils, drained of their cooking water, to the pot. Stir the lentils into the leeks and let them simmer together for a few minutes, tossing from time to time.
Add enough cooking liquid from the lentils to the pot to cover the lentils and leeks entirely, along with the rosemary if using. Simmer everything together for another 5-10 minutes or so.
- If you like a thicker soup (and I often do) crush some of the lentils with a wooden spoon or spatula against the side of the pot as they simmer, as many as you need to get the consistency you prefer. Conversely, if the soup is too thick for your taste, add more liquid, either the cooking liquid from the lentils, broth or water. At the end of cooking, taste and adjust for seasoning.
Serve hot, topped if you like with a drizzle of olive oil or a dusting of freshly grated parmigiano-reggianoor both.
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