Italian Penicillin Soup

The first time I made this Italian Penicillin Soup I was trying to nurse a stubborn cold and wanted something simple that felt like a hug in a bowl.
It wound up being the kind of soup I make when I want comfort without fuss — bright lemon, garlicky broth, and tender vegetables.
It’s quick, forgiving, and uses pantry stalwarts you probably already have.

This recipe is a winner because it balances restorative warmth with fresh acidity.
It’s light enough for a sick day, but flavorful enough to become a weeknight favorite.
And it comes together in under 30 minutes.

Why You’ll Love This Recipe

• Fast: Ready in about 25 minutes from start to finish.
• Nourishing: Simple vegetables and broth make it gentle on the stomach.
• Flexible: Kale or spinach, vegetable broth or a richer stock — it adapts.
• Bright finish: Lemon juice wakes up the whole pot at the end.

The texture is all about contrast: soft, fork-tender carrots and celery swim in a clear, fragrant broth that has a rounded garlic-onion base.
Greens wilt into the hot liquid and keep a pleasant, slightly toothsome bite when you use kale, or become silky and plush if you use spinach.
The lemon juice added at the end cuts any heaviness and gives the soup a lift that makes it feel intentionally balanced, not bland.

“Downloaded this recipe and it was everything I needed—simple, healing, and surprisingly bright. My go-to cold remedy now!” — 5 stars, reader Emily

Key Ingredients

Olive oil
A good extra-virgin olive oil gives the base flavor a rounded, fruity note and helps the onion and garlic release their aromatics without burning. Use a familiar brand you trust for a consistent finish; a robust oil will add depth even if it’s a small amount.

Onion and garlic
Onions provide natural sweetness and body when softened; garlic gives the soup its characteristic kick. Dice the onion small so it melts into the broth, and mince garlic finely so it infuses evenly without sudden bites.

Vegetable broth
This is the backbone of the soup, so quality matters. A low-sodium, well-seasoned vegetable stock lets you control salt while contributing savory complexity. If you have a homemade broth or a good boxed brand like Imagine or Pacific, use it for a cleaner, richer flavor.

Lemon juice
Acid brightens everything and balances the soup’s savory notes. Fresh lemon juice is non-negotiable here — bottled juice lacks the brightness and sharpness that cuts through the olive oil and broth.

Full ingredient list:

• 1 tablespoon olive oil
• 1 onion, diced
• 2 cloves garlic, minced
• 4 cups vegetable broth
• 2 carrots, sliced
• 2 celery stalks, sliced
• 1 teaspoon dried thyme
• Salt and pepper to taste
• 1 cup kale or spinach, chopped
• Juice of 1 lemon

Step-by-Step Instructions

Step 1: Warm the oil

Heat 1 tablespoon olive oil in a large pot over medium heat until it’s shimmering but not smoking.
This gentle heating tempers the oil and creates the right environment to coax out the onion and garlic flavors.
Pro Tip: The oil is ready when it ripples across the pan and releases a faint, warm aroma.

Step 2: Soften the aromatics

Add the diced onion and the minced garlic to the pot and cook, stirring occasionally, until the onion becomes translucent, about 3–5 minutes.
Keep the heat at medium so the garlic doesn’t brown and turn bitter; you want sweet, softened onion and mellow garlic.
Visual cue: The edges of the onion will become glossy and nearly transparent.

Step 3: Add the broth

Pour in 4 cups of vegetable broth and bring the pot up to a gentle simmer.
A simmer rather than a boil keeps the liquid clear and the vegetables tender.
Pro Tip: If your broth is room temperature, it will come to a simmer faster and reduce overall cooking time.

Step 4: Add vegetables and herbs

Stir in the sliced carrots, sliced celery, 1 teaspoon dried thyme, and salt and pepper to taste, making sure the carrots are submerged.
The thyme will release savory notes that anchor the bright lemon later, while submerged carrots cook evenly.
Visual cue: The liquid should barely ripple; large rolling bubbles mean the heat is too high.

Step 5: Simmer until tender

Allow the soup to simmer for 15–20 minutes until the vegetables are fork-tender.
This stage lets flavors meld and sugars from the carrots and onion sweeten the broth.
Pro Tip: Taste at 12 minutes; if the carrots are already soft, reduce simmer time to preserve texture.

Step 6: Finish with greens and lemon

Stir in 1 cup chopped kale or spinach and the juice of 1 lemon just before serving.
Let the greens wilt for about a minute in the hot broth; they should be bright and tender, not overcooked.
Visual cue: Wilted kale will turn a vivid, glossy green and shrink slightly.

Expert Tips for Success

• Control the heat: Medium heat is your friend. Too low and onions won’t soften; too high and garlic will brown. Use a heavy-bottomed pot for even heat distribution.
• Salt in stages: Add a small pinch when you add the broth, then adjust after simmering. If using store-bought broth, taste first to avoid over-salting.

• Choose the right greens: Kale holds up better to reheating and long sits, while spinach gives a silky texture but wilts down much more. Opt for kale when making leftovers.
• Cut vegetables uniformly: Slice carrots and celery in similar thickness so everything cooks evenly during the 15–20 minute simmer.

• Enhance with aromatics: For extra depth, add a bay leaf with the broth or a teaspoon of miso dissolved into a ladle of hot broth before adding back to pot. Don’t overdo it — the soup’s simplicity is its charm.
• Lemon late: Always add lemon juice at the end. Cooking lemon reduces its brightness and can mute the flavor you need to lift the broth.

• Make it heartier: Toss in cooked pasta, small beans, or shredded chicken in the last few minutes if you want a more filling meal. Add them after the greens so they don’t overcook.
• Equipment note: A 4–6 quart pot is ideal — it gives you room to stir and prevents boiling over when simmering.

• Allergy and sodium swaps: Use low-sodium broth and increase herbs for flavor. Swap olive oil for avocado oil if you prefer a neutral taste.
• Fresh vs dried thyme: Use 3 teaspoons fresh thyme if you have it; dried is more concentrated, so a teaspoon suffices.

Storage & Freezing

Fridge: Cool the soup to room temperature no longer than two hours after cooking.
Transfer to airtight containers and refrigerate for up to 4 days.
If you used spinach, expect a softer texture on day two or three; kale will retain structure longer.

Freezer: For longer storage, freeze in portion-sized airtight containers or resealable bags for up to 3 months.
Leave about 1 inch of headspace for expansion.
Tip: Freeze without the lemon and add fresh juice when reheating to preserve brightness.

Reheating: Thaw overnight in the fridge if frozen.
Reheat gently on the stovetop over low-medium heat until just warmed through; avoid boiling to stop greens from disintegrating.
Add a splash of broth or water if it seems too thick, then finish with fresh lemon juice.
Microwave reheating works for single servings; stir halfway through and add lemon at the end.

Variations & Substitutions

• Protein boost: Add shredded rotisserie chicken or canned white beans in the last five minutes for a protein-rich version. The beans will absorb flavors and make the soup more filling.
• Grain add-in: Stir in cooked small pasta like orzo or acini di pepe, or add cooked farro for chewy texture. Add pasta only in individual bowls if you plan leftovers, so it won’t soak up all the broth.
• Spice lift: Add a thin slice of fresh ginger with the garlic for extra warmth, or a pinch of red pepper flakes for a faint heat that pairs well with lemon.
• Creamy twist: For a richer bowl, finish with a swirl of plain yogurt or a tablespoon of mascarpone stirred in off the heat. It softens the lemon’s edge and adds body.

Frequently Asked Questions

What makes this soup a “penicillin” soup?
The term “penicillin” soup is a playful nod to its restorative, cold-fighting qualities: warm broth, garlic, and lemon.
It’s not medicinal, but it’s comforting and soothing for congestion and sore throats.

Can I use chicken broth instead of vegetable broth?
Yes. Chicken broth gives a richer, more savory base and pairs beautifully with the lemon and garlic.
If you use chicken broth, taste for salt before seasoning because many varieties are higher in sodium.

How long will leftovers keep and will the texture change?
Leftovers keep up to 4 days in the refrigerator.
The texture of greens and any added pasta will soften over time; kale holds up best through reheats.

Can I make this soup in a slow cooker or Instant Pot?
You can adapt it: in a slow cooker, use low for 3–4 hours until vegetables are tender.
In an Instant Pot use the sauté function for aromatics, then pressure cook for 3 minutes with a natural release. Add greens and lemon after.

Is there a vegan version?
Yes — the base recipe is already vegetarian and vegan if you use vegetable broth and no dairy.
For added depth without animal products, add a splash of soy sauce or a teaspoon of nutritional yeast.

Final Thoughts

This Italian Penicillin Soup is straightforward, restorative, and endlessly adaptable.
It’s the kind of recipe that gets you through a cold, a busy weeknight, or a low-energy cooking day.
If you try it, please leave a star rating in the recipe card below and pin this to Pinterest so others can find their next comfort bowl.

Conclusion

If you want to compare versions or see similar takes on this classic, check the original community-tested version at Italian Penicillin Soup Recipe.
For a chicken-forward, nostalgic spin that adds tiny pasta, read the helpful walk-through at Italian Chicken Pastina Soup (aka Italian Nonna’s Penicillin Soup).
For a plant-based iteration with additional tips on vegetable-forward flavor, see Italian Penicillin Soup – PlantYou.