National Dish Luxembourg: Zwiwwelsupp (Recipe)
In this article
Discover Zwiwwelsupp, Luxembourg’s much-loved onion soup! Golden, slow-cooked onions, a warming broth, melting cheese and crisp toasted bread come together in a bowl that feels like a hug on a cold day. It is proof that a handful of humble ingredients, treated with patience, can turn into something genuinely memorable — and it belongs on the table at every gathering.
About Zwiwwelsupp
Zwiwwelsupp, the traditional Luxembourgish onion soup, is not merely a dish but a piece of cultural heritage. Its hearty aroma and the combination of onions, cheese and crusty bread make it a warming treat, especially in the colder months. The soup reflects the simple ingredients that characterise Luxembourgish cooking, yet still delivers an unforgettable flavour to the table. Whether shared with friends over a convivial evening or eaten quietly on your own, Zwiwwelsupp always finds its place.
Ingredients (serves 1–2)
- 2 large onions
- 500 ml vegetable or beef stock
- 2 slices of baguette or similar bread
- 100 g grated cheese (goat’s cheese or Gruyère, for example)
- 2 tablespoons butter or oil
- Salt and pepper, to taste
- Optional: fresh herbs, to garnish
Shopping for the ingredients
To make Zwiwwelsupp you will want to gather everything at a well-stocked supermarket or a local market. Choose fresh, firm onions, as they form the very foundation of the dish. It is also worth speaking to a cheesemonger to find a good-quality cheese that will give your soup exactly the flavour you are after. The stock can either be made from scratch or bought ready-made in good quality to keep the preparation quick and straightforward.
Preparing the dish
Before you start cooking, slice the onions into thin rings. This step matters more than it might seem, because thin rings sweeten as they cook and let the aromas develop fully. Next, cut the bread into pieces sized to sit neatly in the bowl later on. Make sure everything is prepared and within reach before you begin, so the cooking process runs smoothly from start to finish.
Step-by-step instructions
- Heat the butter or oil in a large pan and gently sweat the onion rings over medium heat for around 15–20 minutes, until golden brown.
- Pour in the stock and bring to the boil, then reduce the heat and simmer for a further 10 minutes.
- Meanwhile, lightly toast the bread. This gives the soup a pleasant texture.
- Season the soup with salt and pepper, then scatter the grated cheese over the top and let it melt.
- Serve the Zwiwwelsupp piping hot, with the toasted bread alongside.
Gluten-free / lactose-free version
For a gluten-free version of Zwiwwelsupp, use gluten-free bread and check carefully that the stock is gluten-free too. Instead of ordinary butter you can work with a plant-based margarine, which is naturally lactose-free. By choosing these substitution-friendly ingredients you can adapt the dish to a range of dietary requirements without giving up any of its delicious flavour, keeping Zwiwwelsupp a flexible recipe that suits everyone at the table.
Tips for vegans and vegetarians
Vegans can adapt Zwiwwelsupp easily by using vegetable stock and either leaving out the cheese altogether or reaching for a vegan cheese alternative. Take care to use plant-based oils for the cooking. If the onions are fried slowly over a low heat, they release their natural sweetness, which more than compensates for the missing cheese. The result is an aromatic base that impresses even without any animal products — much like a good bowl of Bouneschlupp.
More tips and tricks
Frying the onions until they are properly caramelised gives Zwiwwelsupp a noticeable boost in flavour. You can also add a splash of white wine as you pour in the stock to lend the dish a touch of elegance. Experiment with different cheeses to discover new flavour directions, or add a few cloves of roasted garlic for an extra layer of depth. Small tricks like these make a considerable difference to the finished soup.
Adapting the recipe to your taste
Zwiwwelsupp adapts wonderfully to personal preference. If you like a bit of heat, stir in some chilli or a generous grind of pepper. Extra vegetables such as celery or carrots can be simmered along with the onions to increase the nutritional value and vary the flavour. Even the stock can be swapped for another liquid base to introduce new and exciting notes. Be creative and shape the dish to suit your own palate.
Ingredient substitutions
If you are not keen on onions, try leeks or shallots as the base instead to give the soup an entirely different dimension. The cheese can likewise be replaced with other varieties according to taste, such as feta or Parmesan. When it comes to the stock, a mushroom broth introduces a lovely earthy depth — the same comforting register you find in Gromperesupp. These alternatives mean everyone can tailor Zwiwwelsupp to their own wishes.
Drink pairing ideas
A warming bowl of Zwiwwelsupp goes with a surprising variety of drinks. A lightly chilled, dry white wine is an excellent choice and complements the sweet onion notes beautifully. For an alcohol-free option, freshly pressed apple juice or grape juice is pleasantly refreshing and underlines the sweetness of the onions. Sparkling mineral water or homemade lemonade also round the meal off nicely.
Serving and presentation ideas
To present Zwiwwelsupp attractively, use a handsome serving bowl or individual portion dishes. Garnish the soup with fresh herbs such as parsley or chives to add colour and freshness. A slice of toasted bread laid lightly across the rim of the bowl creates an inviting look. Small details like a final scattering of cheese and a drizzle of good olive oil on the surface make the dish not only prettier but tastier too.
A bit of history
Zwiwwelsupp has its origins in the rural kitchens of Luxembourg, where it was originally prepared as a simple, filling meal. It reflects the need to create something nourishing from modest ingredients, a thrift shared by classics such as Kachkeis Zopp. Over the years it has grown into a cultural symbol and is now found in restaurants and homes alike. Both the making and the eating of this soup are deeply bound up with Luxembourgish identity and with Luxembourgish cuisine as a whole.
More recipe ideas
Summary: Zwiwwelsupp
Zwiwwelsupp is far more than just a soup — it represents the rich tradition and warm-hearted cooking of Luxembourg. Built on simple ingredients and blessed with an unforgettable flavour, it is perfect for sociable evenings or as a hearty supper. Whether in its traditional form or adapted to personal preference, Zwiwwelsupp has something to offer everyone and is a must for anyone wanting to explore Luxembourgish food. Let this delicious dish win you over and savour the flavours of Luxembourg.
