Italian Lentil Soup with Spinach: A Hearty One-Pot Dinner

Italian lentil soup with spinach is a brothy, tomato-scented soup made with lentils, vegetables, herbs, and tender greens. It is an Italian-inspired, practical one-pot meal: the lentils simmer right in the broth, and spinach goes in at the end so it stays green and soft rather than overcooked.

Ingredients

2 tablespoons (30 ml) extra-virgin olive oil
1 medium yellow onion, finely diced, about 1 cup (150 g)
2 medium carrots, diced, about 1 cup (160 g)
2 celery ribs, diced, about 1 cup (100 g)
4 garlic cloves, minced, about 12 g
1 teaspoon (1 g) dried oregano
½ teaspoon (0.5 g) dried rosemary, crushed between your fingers
1½ cups (300 g) brown or green lentils, picked over and rinsed
1 can diced tomatoes, 14½ ounces (411 g), including the juices
6 cups (1.42 L) low-sodium vegetable broth or chicken broth
1 bay leaf
1 teaspoon (6 g) fine salt, plus more to taste; use less if your broth is salty
½ teaspoon (1 g) freshly ground black pepper
5 ounces (140 g) baby spinach, or mature spinach with thick stems removed
1 tablespoon (15 ml) red wine vinegar or fresh lemon juice
¼ cup (15 g) chopped fresh flat-leaf parsley, optional
½ cup (45 g) finely grated Parmesan, for serving; optional

Instructions

Prepare the vegetables and lentils. Dice the onion, carrots, and celery into small, similar-sized pieces so they soften at roughly the same rate. Mince the garlic, then rinse the lentils in a fine-mesh strainer and pick out any small stones or shriveled lentils. Brown and green lentils work well because they keep their shape; there is no need to soak them.
Soften the aromatics. Heat the olive oil in a large, heavy-bottomed pot or Dutch oven over medium heat. Add the onion, carrots, and celery and cook for about 8 minutes, stirring every minute or two, until the onion looks translucent and the carrots begin to soften. They do not need to brown. Stir in the garlic, oregano, and rosemary and cook for 30 seconds, just until fragrant.
Add the lentils, tomatoes, broth, bay leaf, salt, and black pepper. Stir well, scraping the bottom of the pot in case any vegetables have stuck. Raise the heat and bring the soup to a boil, then reduce it to a steady gentle simmer. A few slow bubbles are enough; a hard boil can break the lentils and make the soup cloudy.
Simmer uncovered for 32 minutes, stirring occasionally. Keep the pot at a gentle simmer and check that the lentils are surrounded by liquid. At the end of the cooking time, taste several lentils: they should be tender through the middle but still hold their shape. If they remain firm, continue simmering and check again every 3 to 5 minutes. Older lentils can take longer, and a low simmer is more important than forcing them to cook quickly.
Remove and discard the bay leaf. Stir in the spinach by handfuls and cook for about 3 minutes, until wilted. Turn off the heat, add the vinegar or lemon juice, and taste the broth. Adjust the salt and pepper, adding a little more acid if the soup tastes flat. Stir in parsley if using, then ladle into bowls and offer Parmesan at the table.

Tips

Choose the right lentils. Brown or green lentils are the dependable choice here because they become tender without dissolving immediately. Red or yellow lentils cook faster and break down into a softer, thicker soup, so they are not a direct swap; if using them, start checking much earlier and expect a more puréed texture. Do not substitute canned lentils at the same point in the recipe: add drained, rinsed canned lentils near the end and simmer just long enough to heat them through.
Adjust the liquid after cooking. Lentils absorb broth as the soup sits, so the pot may look looser than you want at first and thicker the next day. Add hot broth or water a little at a time when reheating. If it is too thin, simmer uncovered for a few minutes, stirring so lentils do not catch on the base of the pot.
Keep the spinach bright. Add it only after the lentils are tender, not at the beginning of the simmer. Baby spinach wilts quickly; if using mature spinach, remove tough stems and slice the leaves into manageable pieces. Kale can replace it, but it needs a longer simmer—add chopped kale about 10 minutes before the lentils are done.
Season in layers, then finish with acid. Broth varies in saltiness, so begin with the listed amount only if your broth is low-sodium, and taste before adding more. The vinegar or lemon is not meant to make the soup sour; a small amount sharpens the tomato and herb flavors. Add it gradually if you prefer a milder finish.

Serving Suggestions

Serve the soup hot in wide bowls with grated Parmesan, chopped parsley, and a drizzle of olive oil. Crusty bread, toasted sourdough, or garlic bread is useful for catching the broth and makes the meal more substantial. For a simple side, pair it with a green salad dressed with olive oil and vinegar, or serve roasted vegetables alongside if you are feeding a larger group.

The soup is filling on its own, but you can also spoon it over a small portion of cooked rice or serve it with a cheese toast. Put extra Parmesan and black pepper on the table so everyone can season their bowl. If you are serving guests who avoid dairy, leave off the cheese and offer more olive oil and parsley instead; the broth is flavorful without it.

Variations

For a vegan version, use vegetable broth and omit the Parmesan. If you would like a savory, cheese-like finish, stir a spoonful of nutritional yeast into an individual bowl, though it adds a different flavor rather than reproducing Parmesan exactly. For a more rustic texture, mash a ladleful of cooked lentils against the side of the pot and stir them back into the soup. This thickens the broth without needing flour or cream.

Use Swiss chard in place of spinach by removing the tougher stems, chopping them finely, and adding them with the carrots and celery; add the leaves near the end. For a little heat, add a pinch of red pepper flakes with the garlic. If you want to include small pasta, cook it separately and add it to each bowl just before serving. Cooking pasta directly in the pot can make the soup starchier and leave the noodles over-soft when you store leftovers.

You can use chicken broth for a fuller savory flavor, or vegetable broth to keep the soup meat-free. For a brighter herbal profile, replace the dried oregano and rosemary with about 1 tablespoon (4 g) chopped fresh oregano and 1 teaspoon (1 g) chopped fresh rosemary, adding them near the end of cooking. The dried herbs are convenient and give a deeper, more blended flavor, so either choice works.

Storage and Reheating

Cool leftovers promptly and refrigerate them within 2 hours of cooking in covered, shallow containers. The soup keeps for 3 to 4 days in the refrigerator. Lentils continue to take up liquid as they stand, so expect the chilled soup to be thicker than it was in the pot. Store Parmesan separately and add it when serving.

Reheat a portion in a saucepan over medium-low heat, stirring occasionally and adding a splash of broth or water to loosen it. You can also microwave it in a covered, microwave-safe bowl, stirring halfway through. Reheat leftovers to 165°F (74°C), checking the center with a food thermometer in accordance with USDA FSIS guidance. Avoid repeatedly warming and cooling the whole pot; heat only the portion you plan to eat.

For longer storage, freeze the soup in airtight freezer-safe containers for about 2 to 3 months for best quality, leaving a little room for expansion. Thaw it in the refrigerator overnight or reheat it from frozen over low heat, stirring as it loosens. The spinach may be softer after freezing, but the soup will still be suitable for serving. Add a fresh squeeze of lemon or vinegar after reheating to perk up the flavor.

Frequently Asked Questions

Do I need to soak lentils before making this soup?
No. Brown and green lentils cook in the soup without soaking. Rinse them and check for debris before adding them to the pot. Soaking is unnecessary for this recipe and can shorten the cooking time unpredictably, so rely on tenderness rather than the clock if your lentils are older.

Can I make this soup ahead?
Yes. Make it through the simmering step, cool and refrigerate it, then reheat it and add the spinach just before serving for the freshest color and texture. You can also make the complete recipe ahead; the flavors settle together as it rests, although the lentils will absorb more broth. Add liquid as needed and check that the reheated soup reaches 165°F (74°C).

Why are my lentils still firm after 32 minutes?
Lentils vary in age, and older ones often take longer to soften. Continue cooking at a gentle simmer and check every 3 to 5 minutes. Hard water and acidic ingredients can also slow softening, which is why the tomatoes go into this recipe at the start only with enough cooking time; if your lentils are especially stubborn, simmer until tender rather than serving them firm.

Can I use frozen spinach?
Yes. Thaw it and squeeze out excess water, then stir it into the finished soup until hot. Start with about 1 cup (150 g) thawed, drained spinach and add more to taste; frozen spinach packs differently from fresh leaves. Because it is already wilted, it needs less time than fresh spinach and may make the broth slightly less clear.

How can I make the soup thicker or thinner?
For a thicker soup, mash some of the lentils against the pot or simmer uncovered for a few extra minutes. For a thinner broth, stir in hot water or broth until it reaches the consistency you like. Taste again after changing the liquid, since a splash of broth or water can dilute the seasoning. The soup also thickens naturally in the refrigerator.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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