Irish French Onion Soup with Stout and Cheddar

Irish French onion soup is a French-inspired onion soup made with slowly browned onions, stout, and beef broth, then finished with toasted bread and sharp Irish cheddar. The stout adds a gently malty depth, while the cheese melts into a savory, golden topping; it is a hearty bowl for a cold evening rather than a claim to one traditional Irish recipe.

Ingredients

4 large yellow onions (about 1.2 kg), peeled, halved, and thinly sliced
3 tablespoons unsalted butter (42 g)
1 tablespoon olive oil (15 ml)
1 teaspoon kosher salt (5 g), plus more to taste
1 tablespoon all-purpose flour (8 g)
1 cup dry Irish stout (240 ml), such as a stout with roasted, malty notes
6 cups low-sodium beef broth (1.4 L)
1 teaspoon Worcestershire sauce (5 ml), optional
4 sprigs fresh thyme (about 4 g), or 1 teaspoon dried thyme (1 g)
1 bay leaf
¼ teaspoon freshly ground black pepper (about 0.5 g), plus more to taste
4 thick slices country bread or sourdough, about ½ inch (1.3 cm) thick and 7 oz (200 g) total
1½ cups grated sharp Irish cheddar (150 g)

Instructions

Slice and start the onions. Peel the onions, cut them in half through the root, and slice them thinly from pole to pole. In a large, heavy pot or Dutch oven, melt the butter with the olive oil over medium heat. Add the onions and salt, then toss until coated. Cook for 50 minutes, stirring every few minutes and more often toward the end. If the onions begin sticking or darkening too quickly, lower the heat and add a tablespoon of water. Aim for deeply golden, soft onions, not blackened edges; slow browning creates the soup’s sweetness and savory depth.
Thicken and deglaze. Sprinkle the flour over the onions and stir continuously for 1 minute so it cooks without forming dry clumps. Pour in the stout gradually, scraping the pot with a wooden spoon to release the browned bits. Bring it to a gentle simmer and cook for 4 minutes, stirring once or twice. The beer should lose its sharp, raw aroma and reduce slightly, but it does not need to disappear completely.
Simmer the soup. Add the beef broth, Worcestershire sauce if using, thyme, bay leaf, and black pepper. Bring the pot to a gentle simmer, then cook uncovered for 20 minutes. Keep the soup at a quiet bubble rather than a hard boil, which can make the broth taste less clean. Remove the thyme stems and bay leaf. Taste the broth and add salt or pepper as needed; the cheese will add saltiness later, so season in small increments.
Prepare the bread and broiler. While the soup simmers, set an oven rack so the tops of oven-safe soup crocks will sit several inches from the broiler element. Heat the broiler and arrange four oven-safe crocks on a sturdy baking sheet. If you do not have crocks, toast the bread separately and serve it on top of the soup in regular bowls; do not put non-oven-safe bowls under the broiler.
Fill and top the crocks. Set the crocks on the baking sheet and ladle in the hot soup, leaving about ½ inch (1.3 cm) of space at the top. Place one slice of bread on each crock, trimming it to fit if needed. Divide the grated cheddar evenly over the bread, spreading it close to the edges so it melts across the surface. Keep the baking sheet level as you move it to the oven.
Broil and serve carefully. Broil for about 3 minutes, watching closely from the start, until the cheese is melted, bubbling, and browned in spots. Broilers vary, so remove the crocks sooner if the cheese colors quickly. Use oven mitts to lift the baking sheet, and set each crock on a heatproof plate or trivet. The bowls and soup will be extremely hot; let them stand for a minute before serving.

Tips

Take time with the onions. Slicing them evenly helps them soften at the same pace. If the pot is crowded, use a wide Dutch oven rather than turning up the heat. A little sticking is useful for flavor, but scorched, bitter onion bits are not; lower the heat and loosen browned fond with a splash of water.
Choose a dry stout. A dry, not especially sweet stout gives the broth a rounded roasted flavor. A sweeter or very strong stout can dominate the onions, so use it sparingly or replace it with extra broth. Nonalcoholic stout is another option, though its flavor and reduction may differ slightly. Cooking does not guarantee that all alcohol evaporates.
Make it without wheat. For a gluten-free version, omit the flour and use certified gluten-free broth, stout, bread, and Worcestershire sauce. The soup will be a little less thick, but the long-cooked onions still give it body. Check labels, since beer and Worcestershire sauce can contain ingredients that are not suitable for every diet.
Broil with care. Use only crocks labeled oven-safe, and keep the baking sheet under them in case of drips. If your bowls are not broiler-safe, toast the bread and melt the cheese on it separately, then float each cheesy toast on a bowl of soup. This avoids thermal shock and cracked crockery.

Serving Suggestions

Serve each crock as a meal, since the bread and cheese make the soup filling. A simple green salad with a sharp vinaigrette provides a fresh contrast to the rich broth; lightly dressed bitter greens, such as arugula or watercress, work especially well. Roasted vegetables or steamed green beans are also good side dishes when you want a larger supper without adding another rich course.

For a pub-style table, put extra sliced bread and grated cheddar out for anyone who wants more topping. A small bowl of chopped chives or thyme leaves can add a fresh finish, though neither is essential. If serving a group, keep the soup warm in the pot and broil the bread-and-cheese topping in batches just before eating. Tell guests that the crocks are hot, and give children or anyone who prefers a cooler serving soup in regular bowls with separately toasted bread.

Variations

Use vegetable broth. Replace the beef broth with 6 cups (1.4 L) of full-flavored vegetable broth for a vegetarian version. Choose a stout and Worcestershire sauce that are suitable for your diet; some Worcestershire sauces contain anchovies. The broth will taste lighter than the beef version, so taste before serving and adjust salt and pepper.

Try another cheese. A mature Irish cheddar gives a sharp, distinctly savory finish, but aged English cheddar, Gruyère, or a mix of cheddar and Gruyère also melts well. Gruyère makes the topping more nutty and closer to familiar French onion soup, while a milder cheddar softens the strong beer notes. Grate the cheese yourself if possible, since pre-shredded cheese may not melt as smoothly.

Make it alcohol-free. Use an equal amount of additional beef broth in place of the stout, then add 1 teaspoon (5 ml) of malt vinegar or cider vinegar to the pot for a little brightness. Add the vinegar gradually and taste; it should balance the broth without making it sour. The result will be less malty, but still rich from the browned onions.

Serve the topping separately. For easier everyday serving, toast the bread until crisp, top it with cheddar, and melt the cheese under the broiler on a baking sheet. Set one slice on each bowl just before serving. This version is convenient when you lack oven-safe crocks and keeps the bread from becoming quite as soft in the soup.

Storage and Reheating

For the best texture, store the soup and bread-and-cheese topping separately. Let the soup stop steaming, then refrigerate it within 2 hours in a covered container. It keeps for 3 to 4 days in the refrigerator. Refrigerate leftover bread separately and use it within a day or two; it may soften as it sits. Do not store assembled soup in a crock with the bread on top, because the bread becomes soggy and the crock takes up unnecessary refrigerator space.

Reheat only the amount you plan to serve in a saucepan over medium-low heat, stirring occasionally until steaming throughout. If the soup has thickened, add a splash of broth or water. For food safety, reheat leftovers to 165°F (74°C), checking the center with a food thermometer. Toast fresh bread, add cheddar, and broil it just before serving. The soup, without its topping, can also be frozen in a freezer-safe container for up to 3 months. Thaw it in the refrigerator overnight and reheat as above; the onion texture may be a little softer after freezing.

Frequently Asked Questions

Does Irish French onion soup come from Ireland?

This recipe is an Irish-inspired variation on French onion soup, not a claim that the dish originated in Ireland. It keeps the familiar method of slowly browning onions and serving them beneath bread and melted cheese, while using stout and sharp Irish cheddar for a different flavor. Recipes vary, so there is no single required cheese or beer for every version.

Can I make the soup ahead of time?

Yes. Make the broth through the simmering step, cool it, and refrigerate it promptly for up to 3 to 4 days. Reheat it to 165°F (74°C) before assembling the crocks, then add freshly toasted bread and cheese and broil just before serving. Keeping the topping separate prevents the bread from absorbing the broth in storage.

Why are my onions not turning golden?

They may need more time, a lower-and-steady heat, or a wider pot. Onions first release moisture and soften; browning happens after that moisture cooks away. Stir regularly, but do not stir constantly, since the onions need contact with the hot pot to color. If the bottom is catching, reduce the heat and add a spoonful of water rather than scraping up burnt bits.

What can I use instead of stout?

Use another dry stout, a mild porter, or the same quantity of broth. A porter can be sweeter or less roasted depending on the style, so start with a restrained flavor and taste the broth. For an alcohol-free option with extra brightness, replace the stout with broth and add a small amount of malt or cider vinegar as described above.

Do I need special soup crocks?

No. Oven-safe crocks are useful because the cheese can be browned on each serving, but they are not necessary. Toast bread and melt cheddar on a baking sheet, then place the cheesy toast over soup served in ordinary bowls. Never put a bowl under the broiler unless its manufacturer identifies it as oven-safe.

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