Italian Penicillin Soup: A Cozy Plant-Based Pastina

Italian penicillin soup is a cozy nickname for pastina soup, a simple Italian-style bowl of tiny pasta cooked in savory broth. This plant-based version builds flavor with onion, carrot, celery, garlic, and herbs, then finishes with lemon and nutritional yeast for a bright, savory note. Families make pastina in different ways; this one is an easy vegetable-forward variation, not a claim to a single traditional recipe.

Ingredients

2 tablespoons extra-virgin olive oil (30 ml)
1 medium yellow onion, finely diced, about 1 cup (150 g)
1 medium carrot, finely diced, about 1 cup (130 g)
2 celery ribs, finely diced, about 1 cup (120 g)
2 garlic cloves, finely minced, about 6 g
1 teaspoon fine salt (5 g), plus more to taste
¼ teaspoon freshly ground black pepper (about 0.5 g)
½ teaspoon dried thyme (about 0.5 g)
1 dried bay leaf (about 0.2 g)
9 cups low-sodium vegetable broth (2.13 L)
1½ cups pastina, stelline, or another small pasta (about 225 g)
3 tablespoons nutritional yeast (about 15 g)
1 tablespoon fresh lemon juice (15 ml)
2 tablespoons chopped fresh parsley (about 8 g)
Optional: ¼ cup finely grated plant-based Parmesan-style cheese (about 20 g), for serving

Instructions

Prepare the vegetables. Dice the onion, carrot, and celery into small, even pieces so they soften at roughly the same rate. Mince the garlic and chop the parsley. Measure out the broth, pasta, and seasonings before you start cooking; once the broth is simmering, the pasta needs regular attention.
Soften the aromatics, 8 minutes. Heat the olive oil in a large, heavy-bottomed pot over medium heat. Add the onion, carrot, celery, salt, and pepper. Cook for about 7 minutes, stirring every minute or two, until the onion looks translucent and the vegetables begin to soften. Stir in the garlic and dried thyme and cook for 1 minute. Keep the heat moderate: the vegetables should soften rather than brown heavily, and the garlic should smell fragrant, not toasted.
Simmer the broth and vegetables, 15 minutes. Pour in the vegetable broth and add the bay leaf. Raise the heat until the liquid reaches a gentle boil, then reduce it to a steady simmer. Cook uncovered for 15 minutes, stirring occasionally. The carrot should be tender when pierced with a fork, but the vegetables do not need to fall apart. Taste the broth before adding more salt, since different vegetable broths vary in saltiness.
Cook the pasta, about 9 minutes. Bring the soup back to a gentle boil and stir in the pastina. Cook according to the package timing, usually 6 to 10 minutes, stirring frequently and scraping the bottom of the pot so the small pasta does not stick. Start checking a minute before the package’s suggested time; the pasta should be tender but not mushy. If the pot is bubbling hard, lower the heat to a simmer.
Finish and serve. Turn off the heat and remove the bay leaf. Stir in the nutritional yeast and lemon juice, then taste and adjust the salt, pepper, or lemon. The soup will thicken as the pasta rests, so add a splash of hot broth or water if you prefer it looser. Ladle into bowls and finish with parsley and plant-based Parmesan-style cheese, if using.

Tips

Cut the vegetables small. Pastina is tiny, so finely diced vegetables make each spoonful feel balanced and help the carrot soften on schedule. If you prefer a smoother broth, finely grate the carrot instead of dicing it; it will blend into the soup more readily.
Watch the pasta, not just the clock. Pastina shapes and brands vary, and even a minute too long can turn small pasta soft. Stir often once it goes into the pot and begin tasting before the package’s full cooking time. The pasta continues to absorb liquid after the heat is off.
Season in stages. Low-sodium broth gives you more control, but it still has some salt. Taste after the vegetables have simmered and again after adding the nutritional yeast and lemon. Lemon brightens the flavor; it does not replace salt, so add each in small amounts rather than trying to correct everything with one seasoning.
Plan for thickening. If you expect leftovers, cook the pasta separately and add it to individual bowls, or keep extra hot broth nearby for loosening reheated portions. Pastina steadily absorbs liquid, so a soup that looks brothy in the pot can become quite thick in the refrigerator.

Serving Suggestions

Serve the soup hot as a light main course or as the first course of a larger Italian-inspired meal. A slice of toasted sourdough, crusty bread, or garlic toast is useful for scooping up the broth. For a simple side, offer a green salad dressed with olive oil and vinegar, or serve roasted broccoli or green beans alongside the bowls.

Set lemon wedges, chopped parsley, black pepper, and plant-based Parmesan-style cheese on the table so everyone can finish a bowl to taste. The nutritional yeast adds a gently savory flavor, while the lemon keeps the broth from tasting flat. If your broth is especially robust or salty, begin with a modest garnish and let diners add more at the table.

This recipe makes four modest bowls. For larger appetites, serve generous portions with bread or add a side of white beans. If serving it as a starter, smaller bowls work well before roasted vegetables, a bean dish, or another simple pasta course.

Variations

Change the pasta shape. Pastina means very small pasta, and stelline, acini di pepe, orzo, and small alphabet pasta can all work. Orzo is larger and tends to make the soup feel more substantial; tiny stars or acini di pepe give a more delicate spoonful. Check the package because cooking times differ, and stir often whichever shape you use.

Make it without nutritional yeast. Leave it out for a cleaner vegetable-broth flavor, or stir in a spoonful of plant-based Parmesan-style cheese at the end. The cheese substitute usually adds more salt and may thicken the soup slightly, so taste before adding extra salt. Nutritional yeast is a practical plant-based stand-in for some of the savory, cheese-like character found in versions made with dairy cheese; it is not an exact match.

Add greens or beans. Stir in a packed cup of baby spinach (about 30 g) during the final minute, just until wilted, or add 1 cup drained and rinsed cannellini beans (about 170 g) with the broth for a heartier bowl. Beans make the soup more filling and give it a softer, creamier texture. If adding extra ingredients, taste the broth again before serving.

Use a different herb profile. Substitute ½ teaspoon dried rosemary (about 0.5 g) for the thyme, or add a small pinch of dried oregano. Rosemary has a stronger, woodier flavor, so keep the quantity modest. A strip of lemon zest added with the broth and removed with the bay leaf gives a more fragrant citrus note without making the soup more tart.

Storage and Reheating

For food safety, refrigerate the soup within 2 hours of cooking. Store it in a covered container in the refrigerator for 3 to 4 days. The pasta will continue to absorb broth as it sits, so the leftovers may become thick; that change is normal. For the best pasta texture, store cooked pastina separately from the vegetable broth when you know you will have leftovers, then combine them when reheating.

Reheat soup gently in a saucepan over medium-low heat, stirring often and adding broth or water a little at a time until it reaches the texture you want. Heat leftovers to 165°F (74°C), as recommended by USDA FSIS, checking the center with a food thermometer. A single portion can also be reheated in a microwave-safe bowl; stir partway through and check the temperature in more than one spot.

You can freeze the broth and vegetable base for up to 2 months for better texture, but cooked pastina may become very soft after thawing. Cool the base promptly, freeze it in airtight freezer-safe containers, and thaw it in the refrigerator before reheating. If freezing soup that already contains pasta, expect a softer, thicker result and loosen it with extra broth after reheating. Do not leave the soup at room temperature to cool for an extended period.

Frequently Asked Questions

Why is this soup called Italian penicillin? It is an informal nickname used for pastina soup, a familiar style of small pasta served in broth. The nickname is not a medical claim, and this plant-based recipe is simply a comforting soup made with vegetables, broth, pasta, and seasonings. Recipes differ from household to household, including the kind of broth, pasta, and finishing ingredients used.

What is pastina, and what can I use if I cannot find it? Pastina refers to very small pasta shapes. Stelline, acini di pepe, tiny alphabet pasta, and orzo are practical alternatives; use the package directions to guide cooking and begin tasting early. Orzo is noticeably larger, so the finished soup will have a different bite. If only larger pasta is available, break small noodles into short pieces before cooking.

Can I make the soup gluten-free? Yes. Use a small gluten-free pasta and check that the vegetable broth and any plant-based cheese are labeled gluten-free. Gluten-free pasta can soften quickly and may release more starch, so cook it separately if you want better control over texture, then stir it into the broth just before serving. Follow the pasta package timing rather than assuming it cooks like wheat pasta.

Can I make it ahead? You can prepare the vegetable broth base up to 3 days ahead and refrigerate it in a covered container. Reheat the base, bring it to a gentle boil, and cook the pastina shortly before serving. This keeps the pasta from swelling in storage. If the whole soup is already made, it is still fine to store for 3 to 4 days, but expect it to thicken and soften.

How can I make the soup more brothy? Add hot vegetable broth or water a little at a time, stirring until the soup reaches the consistency you like. For a soup that will be stored, keep the pasta and broth separate when possible and combine them at serving time. Adding liquid at the end is easier than trying to correct a pot that has become too thin, so start with a small splash and taste as you go.

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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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