Caramelisation is the slow browning that turns ordinary onions soft, sweet, and deeply golden. That rich onion flavour is what makes Delia Smith French Onion Soup Recipe so good, especially with crunchy garlic bread and melted Gruyère cheese on top.
Ingredients
This recipe serves 6 people and takes approximately 2 hours to prepare and cook.
For the Soup:
700g (1½ lb) onions, peeled and thinly sliced
2 tablespoons olive oil
50g (2 oz) butter
2 garlic cloves, crushed
½ level teaspoon granulated sugar
1.2 litres (2 pints) beef stock
275ml (10 fl oz) dry white wine
2 tablespoons Cognac (optional)
Salt, to taste
Freshly ground black pepper, to taste
For the Garlic Croutons:
6 large or 12 small slices of French bread or baguette
1 tablespoon olive oil
1–2 garlic cloves, crushed
For the Cheese Topping:
– 225g (8 oz) Gruyère cheese, freshly grated
Use ordinary brown or yellow onions for this recipe. They have a good balance of sweetness and sharpness, which changes beautifully during cooking. Gruyère is my preferred cheese here because it melts smoothly and has a nutty flavour that goes well with the onions.
How to Make Delia Smith French Onion Soup
Step 1: Prepare the Garlic Croutons
Preheat your oven to 180°C (350°F), Gas Mark 4. Pour one tablespoon of olive oil onto a baking tray, add the crushed garlic, and spread it around so the oil picks up the garlic flavour.
Place the bread slices on the tray and turn them over to coat both sides lightly. Bake for about 20–25 minutes until the bread is golden and crisp. Keep an eye on the thinner slices because they can brown sooner.
Once ready, remove the croutons from the oven and leave them aside. They should be quite crunchy because they will soften slightly after being placed on the hot soup.
I prefer making the croutons before starting the onions. It keeps the final preparation simple, and there is no need to rush while the soup is finishing.
Step 2: Slowly Caramelise the Onions
Place a large, heavy-bottomed saucepan over high heat. Add the butter and two tablespoons of olive oil, allowing the butter to melt completely.
Add the thinly sliced onions, crushed garlic, and sugar. Stir frequently for about 6 minutes until the onions soften and begin developing brown edges.
Now turn the heat down to its lowest setting. Continue cooking the onions for approximately 30 minutes, stirring occasionally so they brown evenly without burning.
You want the onions to become deep golden brown, very soft, and noticeably sweet. Some brown residue will also collect at the bottom of the saucepan. That is normal and will add flavour once the stock goes in.
Don’t try to speed up the caramelising stage by increasing the heat. Burnt onions will give the whole soup a bitter taste. If they begin sticking too much, add a small splash of water and stir gently.
Step 3: Add the Stock and Finish the Soup
Once the onions have caramelised, pour in the beef stock and dry white wine. Season with salt and freshly ground black pepper, then stir well.
Use a wooden spoon to scrape the browned onion residue from the bottom of the saucepan. Bring everything to a gentle simmer and leave it uncovered for approximately 1 hour, stirring occasionally.
The onions will become extremely tender, while the broth develops a rich brown colour. Taste the soup near the end of cooking and adjust the seasoning. Add the Cognac if you are using it.
When ready to serve, preheat your grill to its highest setting. Ladle the hot soup into six ovenproof bowls, leaving enough room for the bread and cheese.
Place a large garlic crouton, or two smaller ones, over each bowl. Cover generously with freshly grated Gruyère.
Put the bowls on a sturdy baking tray and grill for 2–4 minutes until the cheese melts and begins turning golden brown. Watch carefully because the cheese can burn quickly.
Serve immediately while the cheese is bubbling. The bowls will be very hot, so handle them carefully.
What to Serve With Delia Smith French Onion Soup
French onion soup is already quite filling because of the bread and cheese. I think lighter dishes make the best accompaniments, particularly if you’re serving generous portions.
Green Salad: Fresh lettuce, rocket, cucumber, and a simple lemon dressing add a pleasant contrast to the rich broth.
Roasted Vegetables: Roasted carrots, courgettes, or asparagus go well with the sweet onions without making the meal too heavy.
Crusty Baguette: Extra French bread is useful for dipping into the broth, especially for anyone who enjoys soaking up every last spoonful.
Grilled Chicken: A small serving of grilled chicken makes a good addition if you want something more substantial for dinner.
Personally, I enjoy serving Delia Smith French Onion Soup Recipe as a starter before roasted meat or chicken. The soup has plenty of flavour, so the following course doesn’t need an elaborate sauce.
Delia Smith French Onion Soup Nutrition Information
The following nutritional values are approximate estimates per serving, based on six portions with bread, cheese, and the optional Cognac.
Nutrient | Amount per serving |
|---|---|
Calories | 460 kcal |
Protein | 20g |
Carbohydrates | 36g |
Fat | 26g |
Saturated Fat | 13g |
Fibre | 4g |
Sugars | 10g |
The actual amounts depend on the bread, cheese, and stock used. Beef stock can also contain a considerable amount of salt, so taste the soup before adding extra seasoning.
FAQs
Can I make French onion soup ahead of time?
Yes. You can prepare the soup up to 3 days ahead and keep it refrigerated in an airtight container. Reheat it thoroughly and add the freshly toasted bread and cheese just before serving.
What are the best onions for French onion soup?
Brown or yellow onions are my first choice. They become naturally sweet during slow cooking and produce a rich flavour without needing much additional sugar.
Can I make French onion soup without wine?
Yes. Replace the wine with the same amount of beef stock. A small splash of lemon juice or white wine vinegar can add some acidity, although the flavour won’t be exactly the same.
Can I freeze French onion soup?
Yes. Allow the soup to cool, then freeze it without the bread or cheese in suitable airtight containers for up to 3 months. Defrost overnight in the refrigerator and reheat thoroughly before serving.
Why does my French onion soup taste bitter?
The onions may have burned during cooking. They should become deep brown but never black. Keep the heat low during caramelisation and stir occasionally to prevent scorching.
Can I use Cheddar instead of Gruyère?
Yes, although the flavour will change. Mature Cheddar has a stronger, sharper taste, while Gruyère is nuttier and melts more smoothly. Comté and Emmental are also good alternatives.
How do I thicken French onion soup?
Traditional French onion soup usually has a fairly thin broth. If yours seems too watery, simmer it uncovered a little longer to reduce the liquid. Avoid adding too much flour because it can make the soup heavy.
Why do the croutons become soggy?
Bread naturally absorbs liquid once it touches the soup. Toast the slices until completely crisp, add them immediately before grilling the cheese, and serve the soup without leaving it standing for too long.