RecipesFrom the test kitchen
Lentil and Spinach Soup
A one-pot, iron-focused lunch soup that finishes with fresh spinach and a squeeze of lemon so the vitamin C lands right next to the plant iron.
This is the lunch soup we point to when someone asks how to get more iron from plants without eating the same salad twice a day. Brown lentils simmer with onion, carrot, garlic, and cumin in one pot, then a big pile of fresh spinach wilts in off the heat and a squeeze of raw lemon juice goes in last. The lemon is not just for brightness. Vitamin C helps your body absorb non-heme iron, the kind found in lentils and spinach, so the order of operations here is doing real nutritional work. Each bowl lands around 4.5 mg of iron, 7 g of fiber, and roughly 690 mg of potassium based on the USDA figures behind our index.
Method
- 1
Warm the olive oil in a large pot or Dutch oven over medium heat. Add the onion and carrots with a pinch of salt and cook for 5 to 6 minutes, stirring now and then, until the onion turns translucent and the carrots start to soften.
- 2
Stir in the garlic and cumin and cook for 1 minute, just until fragrant. If you are using whole cumin seed, let it sizzle in the oil so it toasts.
- 3
Add the rinsed lentils and the water or broth. Bring to a boil, then drop the heat to a gentle simmer. Cook uncovered for 25 to 30 minutes, until the lentils are tender but still hold their shape.
- 4
Taste and season with salt and black pepper. If the soup looks thicker than you like, thin it with a splash of hot water.
- 5
Turn off the heat, add the spinach in two big handfuls, and stir. It will look like too much, then wilt down into the soup within a minute.
- 6
Stir in the lemon juice off the heat so its vitamin C is not cooked away. Taste one more time and adjust salt.
- 7
Ladle into four bowls and serve hot, with an extra lemon wedge on the side if you like it sharper.
Why this scores well
Original analysis by NutriVerdict
The two headline ingredients here are also two of the strongest performers in our index. Raw spinach scores a perfect 100 on our Nutrient Density Score, packing 2.71 mg of iron, 2.2 g of fiber, and 558 mg of potassium into every 100 g for only 23 calories. Raw lentils score 70 and carry the heavy load: 6.51 mg of iron, 10.7 g of fiber, and 677 mg of potassium per 100 g, which is why one cup of dry lentils supplies most of this pot's minerals. Lemon juice (90) contributes 38.7 mg of vitamin C per 100 g, the absorption helper for all that plant iron. Cumin seed (95) is quietly one of the most iron-dense items in the entire database at 66.4 mg per 100 g, so even a teaspoon adds a measurable bump. Carrots (94), garlic (80), and onions (67) round out the base. Add it up and each bowl delivers about 4.5 mg of iron, 7 g of fiber, and roughly 690 mg of potassium.
Tips
- Add the lemon juice off the heat, always. Vitamin C is heat-sensitive, and it is the piece of this recipe that helps your body pull more iron out of the lentils and spinach.
- Skip coffee or tea with this meal if iron is your goal. The polyphenols in both can get in the way of non-heme iron absorption, so save them for an hour or two later.
- The soup thickens a lot in the fridge as the lentils keep drinking the broth. Reheat with a splash of water and a fresh squeeze of lemon and it comes right back.
What this plate is built on
This recipe leans on foods that are good sources of protein, dietary fiber, iron, potassium and magnesium. The recipe density score above is the average Nutrient Density Score of its whole foods, computed the same way for every recipe on the site.
Storage and make-ahead
Store the cooled soup in an airtight container in the fridge for up to 4 days, where it thickens as the lentils keep drinking up the broth, so loosen it with water or broth when you reheat. It freezes well for up to 3 months in single portions, though the spinach loses some structure after thawing. Reheat gently on the stove and add a fresh squeeze of lemon after warming to wake the flavor back up.
Variations and swaps
- Swap the spinach for chopped kale or Swiss chard, adding the sturdier greens about 10 minutes earlier so they soften.
- Fold in a can of diced tomatoes with the broth for a brighter, more stew-like base.
- Shift the seasoning toward North Africa with 1/2 teaspoon each of coriander and smoked paprika alongside the cumin.
What to serve it with
Serve it with warm pita or crusty bread to mop the bowl, and a dollop of plain yogurt swirled in for creaminess if you like. A simple side salad or a scoop of cooked rice stirred in turns a starter portion into a full, sit-down meal.
Note: This is food, not medical advice. The iron in lentils and spinach is non-heme iron, which your body absorbs less readily than the iron in meat, and that is exactly why the lemon finish matters: vitamin C eaten in the same meal improves non-heme iron uptake. All nutrient figures come from the USDA FoodData Central records behind our index.
Frequently asked questions
Do I need to soak the lentils first?
No. Brown and green lentils cook straight from dry in about 25 to 30 minutes, no soaking needed. Just rinse them and pick out any small stones or shriveled ones before they go in the pot.
Can I use red lentils instead?
You can, but expect a very different texture. Red lentils break down into a thick, almost pureed soup in 15 to 20 minutes, while the brown or green lentils here hold their shape. If you switch, add the spinach a touch earlier since the whole thing cooks faster.
Why is the lemon juice added at the end?
Stirring in the fresh lemon juice off the heat keeps its brightness and its vitamin C, which helps your body take up the plant iron from the lentils and spinach. Cooking acid for a long time dulls both the flavor and that benefit, so save it for the finish.
Can I make it heartier for dinner?
Yes. Stir in a cup of cooked bulgur or a peeled, diced potato with the broth, or double the lentils for a thicker, stew-like pot. Add a little extra water or broth if it tightens up too much as it sits.
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