This rich and savory soup is a hearty twist on a classic, perfect for warming up during cold winter months. It combines deeply caramelized onions with a flavorful broth and a cheesy baguette topping.

List of ingredients

8 cups chopped onions – yellow onions provide the best balance of sweetness and savoriness.
1/4 cup salted butter – used for sautéing and enriching the base.
1 1/2 tbsps minced garlic – adds a pungent, aromatic depth.
1/4 cup flour – serves as a thickening agent for the broth.
1/4 cup apple cider vinegar combined with 1/4 cup water and 1 tbsp maple syrup – a non-alcoholic substitute for whiskey to provide tang and sweetness.
8 cups beef broth – the primary liquid base for a deep flavor.
2 bay leaves – provides a subtle herbal background.
2 tsps thyme – adds an earthy, lemony aroma.
1-2 dashes Worcestershire sauce – enhances the umami profile.
Sea salt and pepper to taste – essential for balancing all the flavors.
Better Than Boullion Beef Base (optional) – used to add extra richness if the broth tastes thin.
1 French baguette, sliced – used for the toasted topping.
Mozzarella cheese – herb and garlic variety is recommended for extra flavor.

step-by-step instructions

Brown the onions: Melt the butter in a large pot over medium-high heat. Add the onions and stir frequently for 30-40 minutes until they are deeply browned; add a splash of beef broth or more butter if they begin to stick to the bottom.
Incorporate aromatics: Stir in the minced garlic and flour. Cook for about one minute to remove the raw flour taste.
Deglaze the pot: Pour in the apple cider vinegar and maple syrup mixture. Scrape the bottom of the pan to release the browned bits and simmer for 8-10 minutes over medium heat.
Simmer the base: Add the beef broth, bay leaves, thyme, Worcestershire sauce, sea salt, and pepper. If the soup lacks richness, stir in a heaping spoonful of beef bouillon.
Slow cook: Let the soup simmer over medium heat for 35 minutes to allow the flavors to meld.
Prepare for baking: Preheat your oven to 425F.
Assemble and broil: Ladle the soup into oven-safe bowls. Place baguette slices on top, cover generously with mozzarella cheese, and bake for 5-10 minutes until the cheese is golden and bubbly.

Mastering the Caramelization Process

Maintaining Steady Heat for Onions

Keep the pot on medium-high heat to ensure the onions brown evenly without burning. If the heat is too high, the onions will char and become bitter instead of sweet. Constant stirring is necessary to distribute the heat across all the onion pieces.

Deglazing the Pot for Maximum Flavor

The brown bits stuck to the bottom of the pot, known as fond, contain concentrated flavor. Using the vinegar and syrup mixture helps lift these particles back into the soup. Ensure you scrape every corner of the pot for a richer result.

Preventing Onion Residue from Burning

If you notice the onions sticking too aggressively to the pan, do not let them burn. Add a small amount of butter or a splash of beef broth to loosen the ingredients. This maintains the moisture level and prevents the sugar in the onions from scorching.

Timing the Flour Addition

Add the flour only after the onions have achieved a deep brown color. Stirring the flour for a full minute ensures the starch cooks through, which prevents the final soup from having a raw grain taste. This also helps the flour effectively thicken the broth later.

Optimizing Your Ingredient Selection

Choosing the Right Onion Variety

Yellow onions are the industry standard for this recipe because they offer a strong flavor that mellows into sweetness. Red onions can be used but may change the color of the soup to a darker, less traditional hue. White onions are milder and may require a longer cooking time to reach the same sweetness.

Selecting a Rich Beef Base

Using a high-quality beef broth provides the foundation for the soup’s depth. If the broth tastes watered down, a concentrated beef base can bridge the gap. Ensure the base is free from pork-derived additives to maintain the intended dietary profile.

Comparing Mozzarella and Other Cheeses

Mozzarella provides a great stretch and a mild flavor that complements the onions. For more complexity, an herb-infused mozzarella adds an extra layer of aromatics. Ensure the cheese is freshly grated for the smoothest melt during the baking process.

The Role of Fresh Thyme

Fresh thyme provides a brighter, more citrusy note than dried thyme. If using dried herbs, reduce the quantity slightly as the flavor is more concentrated. Add the thyme during the simmering stage to allow the oils to infuse into the broth.

Serving and Presentation Guide

Prepping Baguettes for Maximum Crunch

Allow the baguette to sit out overnight to dry out slightly before slicing. This creates a sturdier piece of bread that can support the weight of the cheese. Stale bread absorbs the soup without becoming immediately mushy.

Selecting Oven-Safe Soup Crocks

Use ceramic or stoneware bowls that are specifically labeled as oven-safe. These materials distribute heat evenly, ensuring the soup is hot while the cheese browns. Avoid using plastic or thin glass containers that could crack under high heat.

Perfecting the Cheese Melt

Place the cheese slices directly on top of the bread to create a seal. This prevents the bread from soaking up too much liquid too quickly. Bake until the cheese is bubbling and has small golden-brown spots.

Adding Fresh Garnishments

A sprinkle of fresh parsley or a few thyme leaves on top of the melted cheese adds a pop of color. This contrast makes the dish more visually appealing. Serve immediately while the cheese is still stretchy and hot.

Storage and Preservation Methods

Cooling the Soup Safely

Let the soup cool to room temperature before transferring it to the refrigerator. Cooling too slowly can risk bacterial growth, so divide large batches into smaller containers. This allows the soup to reach a safe temperature more quickly.

Optimal Container Selection for Storage

Use airtight glass containers to keep the soup fresh and prevent it from absorbing other fridge odors. Glass is preferable to plastic as it does not stain from the rich beef broth. Store the soup separately from the bread and cheese.

Freezing Without Ruining Texture

The soup base can be frozen for up to three months in freezer-safe bags or containers. Leave a small amount of space at the top to allow for expansion during freezing. Avoid freezing the soup with the bread and cheese already added.

Managing Liquid Loss During Storage

The soup may thicken as it sits in the refrigerator due to the flour and gelatin in the broth. When you are ready to eat it, you may need to add a splash of water or broth. This restores the original consistency without altering the flavor.

Reheating Guidelines for Best Results

Simmering for Consistency

Reheat the soup on the stovetop over low to medium heat. Stirring occasionally prevents the bottom from scorching and ensures the heat is distributed evenly. Bring the liquid to a gentle simmer rather than a rolling boil.

Avoiding Microwave Overheating

If using a microwave, heat the soup in short intervals and stir in between. This prevents hot spots and ensures the liquid is heated uniformly. Be careful not to overheat, as this can break down the emulsified fats in the broth.

Refreshing the Flavor Profile

After reheating, taste the soup to see if it needs a pinch of salt or a dash of pepper. A small amount of fresh thyme added at the end can revive the aromatic qualities. This makes the reheated soup taste as fresh as the original batch.

Adding the Topping After Reheating

Always toast the bread and melt the cheese only after the soup has been fully reheated. Placing cold bread on hot soup and then baking it ensures the maximum crunch. This prevents the baguette from becoming soggy during the reheating process.

Flavor Customization and Variations

Adding Mushrooms for Earthiness

Sautéing sliced cremini or button mushrooms with the onions adds a deep, earthy layer of flavor. Cook the mushrooms until they have released their moisture and browned. This complements the beef broth and enhances the overall savoriness.

Substituting Beef Broth for Vegetable Broth

For a lighter version, you can replace the beef broth with a rich vegetable broth. Use a dark vegetable stock to maintain the visual appeal of the dish. You may need to increase the amount of beef base or soy sauce to keep the umami depth.

Balancing the Acidity Levels

If the soup tastes too acidic from the vinegar, add a pinch of sugar or a small amount of maple syrup. The sweetness neutralizes the sharp edges of the acid. Taste the soup frequently during the final simmer to find the right balance.

Increasing the Savory Depth

Adding a teaspoon of tomato paste during the flour stage can deepen the color and flavor. This adds a subtle sweetness and a more robust body to the broth. It works well with the caramelized onions to create a complex taste.

Common Cooking Troubleshooting

Thickening a Watery Soup

If the soup is too thin, you can create a small slurry of cornstarch and water and stir it in. Alternatively, simmer the soup for an extra 15-20 minutes without a lid to reduce the liquid. This concentrates the flavors and thickens the consistency.

Reducing Excessive Saltiness

If the broth becomes too salty, add a peeled potato and simmer it in the soup for 10 minutes. The potato absorbs some of the salt before you remove it. Alternatively, adding a bit more water or unsalted broth can dilute the salinity.

Handling Clumps of Flour

If the flour clumps during the initial stir, use a whisk to break them up as you add the liquid. If clumps persist, you can pass the soup through a fine-mesh strainer. This ensures a smooth, professional texture throughout the dish.

Preventing Cheese from Burning

Keep a close eye on the oven during the final baking stage. Because the oven is at 425F, the cheese can go from golden to burnt very quickly. Remove the bowls as soon as the cheese is bubbly and lightly browned.

Frequently Asked Questions

Can I use a different bread?

Yes, you can use sourdough slices or toasted ciabatta if a baguette is unavailable. Ensure the bread is toasted or slightly stale to prevent it from dissolving into the soup. The goal is to have a sturdy base for the cheese.

How long does this soup last?

The soup base stays fresh in the refrigerator for 4 to 5 days. When stored in an airtight container, the flavors often improve after the first day. Always reheat to a simmer before serving.

What is the best beef base?

A high-quality beef base that is concentrated and rich in minerals is best. Look for brands that use real beef stock rather than just flavorings. This provides the necessary body and mouthfeel for a traditional onion soup.

Can I make this in a slow cooker?

While you can simmer the broth in a slow cooker, the onions must be caramelized in a pan first. Slow cookers cannot reach the temperature necessary to brown onions properly. Once caramelized, combine everything in the slow cooker on low for 6-8 hours.

Irish Onion Soup

Author: AlmaHerzog
Total Time: 80 minutes
Yield: 12 cups 1x
Diet: General

Print Recipe

Description

A non-alcoholic twist makes this French Onion Soup inspired recipe Irish!

Ingredients

Scale

8 cups chopped onions
1/4 cup salted butter
1 1/2 tbsps minced garlic
1/4 cup flour
1/2 cup non-alcoholic whiskey alternative
8 cups beef broth
2 bay leaves
2 tsps thyme
1–2 dashes Worcestershire sauce
Sea salt and pepper to taste
Optional beef base
1 French baguette, sliced
Mozzarella cheese

Instructions

Brown: In a large pot, over medium-high heat, add the butter and onions, stir. Brown the onions for 30-40 minutes, stirring often.
Thicken: Add the garlic and flour and stir for roughly a minute.
Deglaze: Add the non-alcoholic whiskey alternative and scrape the bottom of the pan. Get all the bits and simmer for 8-10 minutes, over medium height.
Simmer: Add the beef broth, bay leaves, thyme, Worcestershire sauce, sea salt, and pepper. Taste and if it’s not rich add a heaping spoonful of beef bouillon. Simmer over medium heat for 35 minutes.
Prepare Oven: Preheat oven to 425F.
Assemble: Ladle the soup into french onion bowls, and top with the slices of the baguette.
Melt: Layer on the cheese and bake for 5-10 minutes until the cheese gets golden and bubbly.

Notes

Let the baguette sit out overnight so it crusts up. Keep a close eye on the onions as they brown to prevent them from burning.

Prep Time: 15 minutes
Cook Time: 65 minutes
Category: Soup
Method: Stovetop and Baking
Cuisine: American

Nutrition

Serving Size: 1 cup
Calories: 411 kcal
Sugar: 8.9 g
Sodium: 1327.5 mg
Fat: 6.6 g
Saturated Fat: 3.1 g
Unsaturated Fat: 3.5 g
Trans Fat: 0 g
Carbohydrates: 65 g
Fiber: 4.2 g
Protein: 23.1 g
Cholesterol: 15.3 mg

Keywords: Irish onion soup, onion soup