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Carabaccia – Tuscan Red Onion Soup

Name: Italian Red Onion Soup (Carabaccia)
Prep time: 20 min
Cook time: 60 min
Total time: 110 min
Ingredients: 8 Tbsp Butter; 6 cups Red Onions (sliced or chopped); 3 Cloves Garlic; 1 tsp sugar; 1 ¼ cups Red Wine (such as Cabernet Sauvignon); 8 cups Beef Stock; 1/3 cup Flour; 1 cup Tomato Sauce; 2 tsp Salt; ¼ tsp Pepper; 1 tsp Thyme

ByEnza Whiting March 1, 2022July 25, 2025 Updated onJuly 25, 2025

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Carabaccia, also known as Tuscan Red Onion Soup, is rich in flavor from slow cooked sweet red onions and full-bodied wine they cook in. This delicious Tuscan soup is the original onion soup that very few people outside of Italy know about!

A white bowl filled iwth Italian Onion soup topped with a piece of toasted baguette and melted cheese.

Table of Contents

Believe it or not, I first had Italian red onion soup at an American friend’s house! I’d never even heard of it before, but one spoonful and I was hooked—I had to get the recipe. Then, after learning its history, it’s become my go-to recipe for onion soup.

A Bit of History

Carabaccia originated in 15th-century Tuscany. Traditionally made with local red onions, it had a sweet-and-sour flavor and was thickened with ground almonds. A slice of bread went into the bowl first, then the soup was poured over and topped with cheese—sound familiar?

Legend has it that Catherine de’ Medici brought the recipe to France when she married King Henry II, and apparently, it was a favorite of Leonardo da Vinci.

Over time, the recipe evolved. Modern versions often skip the almonds and include additions like a poached egg or spring vegetables like fava beans or peas.

Why This Recipe Works

Like many home cooks, I’ve made a few changes based on what my family loves.

Savory over sweet: This version skips the traditional almonds and sweet-sour balance in favor of a more robust flavor profile.
The red onions are gently sweated: Cooking the onions low and slow helps mellow their sharpness and bring out their natural sweetness without caramelizing them.
Flour as a thickener: Replacing the crushed almonds with a small amount of flour creates a slightly creamy texture without changing the flavor of the broth.
Layers of flavor: Red wine, beef stock and tomato sauce work together to create a rich, slightly tangy broth that complements the onions perfectly!

Carabaccia Ingredients and Notes

Ingredients for needed for making Tuscan Onion Soup with labels over each item.

Red Onions are the star ingredient in this soup. I recommend slicing them rather than chopping them so they hold their shape and texture and don’t completely melt into the broth.
Red Wine, such as a Cabernet, adds a deep, robust flavor that balances well with the sweetness of the onions.
Tomato Sauce isn’t a traditional ingredient in classic Carabaccia, but I love the subtle tang it brings to the dish, reminiscent of the sweet and sour flavors in the original.
Flour replaces the crushed almonds from the original recipe and acts as a thickener. Combined with the tomato sauce, it gives the soup a slightly creamy consistency without overpowering the other ingredients.

Tuscan Onion Soup Recipe Variations

To make this recipe vegan or vegetarian, sweat the onions in olive oil and replace the beef stock with vegetable broth.
For a gluten-free version, the flour can be replaced with 1/2 cup of ground almonds, which can be added to the onions before stirring in the wine. Another alternative is to add a cornstarch slurry after the wine is reduced.

Step-by-Step Instructions

Sliced red onions in a pan, with chopped garlic.

Step 1: Melt butter in a large soup pot and add sliced red onions, minced garlic and sugar.

Sliced red onions that have been softened in a white pan.

Step 2: Cook the onions slowly over low heat until they are soft, about 20 minutes.

Step 3: Add red wine to the onions, bring it to a boil then lower the heat and cook until it is reduced by half.

Step 4: Whisk the tomato sauce and the flour in a small bowl until creamy and no lumps remain. Stir it into the onion mixture.

A beef broth soup cooking in a dutch oven.

Step 5: Stir in the beef stock, Thyme, salt and black pepper.

Step 6: Bring the soup to a boil, then cover and lower the heat and let it simmer for 40 minutes. Uncover and let the soup continue to cook uncovered for 20 minutes. Top with shredded fontina cheese.

bowl of red onion soup topped with shredded fontina cheese.

Cooking Tip

To bring out the best flavor from the onions, cook them slowly so that they don’t burn. Be patient!

Serving Recommendations for Carabaccia

We love to serve our Tuscan onion soup with bread and melted cheese. Before serving, place a slice of toasted bread in the bottom of each bowl, then ladle the soup over it. Top with shredded fontina or mozzarella cheese and put it under the broiler for a minute or just until the cheese has melted.

In some parts of Italy, an egg is broken into the soup and cooked just long enough for the whites to set.

Two bowls of Carabaccia, Italian Onion Soup topped with a slice of bread and melted cheese.

Carabaccia FAQs

Is there a difference between onion soup and French onion soup?

There is a difference between French onion soup and other onion soup recipes. French onion soup is always made with white onions and beef stock. Carabaccia or Tuscan onion soup is made with red onions and other onion soup recipes can be made with a variety of onions and may use vegetable, chicken, or beef stock.

What do you serve with Onion Soup?

Onion soup can be served as a first course or a main course. As a first course, it pairs well with many dishes such as Garlic and Herb Roast Chicken or Balsamic Pork Tenderloin. It is also a wonderful companion to a green salad such as Caesar, garden, spinach, or any crunchy leafy blend.

2 Comments

Karen says:

April 22, 2023 at 2:32 pm

Flavor is wonderful, but onions all but dissolved during the summer phase. 🤔

Reply
John says:

March 3, 2022 at 7:18 am

Flavor is outstanding.

Reply