Zwiebelkuchen

Ingredients

• 250 gplain flour
• 1 teaspoondried yeast
• 1 teaspoonsugar
• A pinchsalt
• 150 mllukewarm water
• 2 tablespoonsolive oil
• 800 gonions
• 2 tablespoonsbutter
• 150 gbacon lardons
• 200 gsour cream
• 2eggs
• A pinchnutmeg
• To tastesalt and pepper

Instructions

1. 1

   Make the dough

   Mix the flour, dried yeast, a pinch of salt and the sugar. Add the lukewarm water and olive oil, then knead until smooth. Cover and leave to rise in a warm place for 45 minutes.

2. 2

   Braise the onions

   Meanwhile, melt the butter in a large frying pan over a medium heat. Add the onions, sliced into thin rings, and a pinch of salt. Cook over a low heat for 25 to 30 minutes, stirring regularly, until soft and golden. Leave to cool slightly.

3. 3

   Cook the bacon

   Fry the bacon lardons in a dry pan until crisp. Drain on kitchen paper and set aside.

4. 4

   Mix the filling

   Whisk the sour cream with the eggs, a pinch of nutmeg, salt and pepper. Stir in the braised onions and bacon.

5. 5

   Heat the oven

   Preheat the oven to 200°C.

6. 6

   Line the tin

   Lightly grease a 25 cm tart tin. On a floured work surface, roll the risen dough into a round large enough to cover the base and sides of the tin. Press it gently into place.

7. 7

   Fill the tart

   Spoon the onion mixture evenly over the dough and smooth the top.

8. 8

   Bake and rest

   Bake in the middle of the oven for 30 to 35 minutes, until golden and cooked through, with a set filling and lightly crisp edges. Leave to rest for 10 minutes before slicing. Serve warm, optionally with a fresh green salad.

What is Zwiebelkuchen?

Zwiebelkuchen, or onion cake, is a savoury tart associated with Germany and the neighbouring Alsace region. Its generous onion filling and simple yeasted base make it a substantial dish for sharing.

This version pairs slowly braised onions with bacon, sour cream and eggs. The dough gives the creamy filling a sturdy, lightly crisp-edged shell.

Nutrition and macros by portion

The nutrition label shows one serving as written: 500 calories, 16g protein, 45g carbs, 27g fat.

The flour and onions provide most of the carbohydrates, while the olive oil, butter, bacon, sour cream and eggs contribute much of the fat. Eggs, bacon and flour also supply protein. Serve a slice with a generous green salad to add freshness and balance the plate.

Build a soft, sturdy base

Yeasted dough: kneading the flour, water, yeast and oil into a smooth dough gives the tart a bread-like base that can support the filling. Allow the full 45 minutes for it to rise in a warm place.

Tin fit: roll the dough wide enough to cover both the base and sides of the 25 cm tin. Press it in gently rather than stretching it thin.

Give the onions time

Low heat: the onions need 25 to 30 minutes in butter to become soft and golden without scorching. Stir them regularly, especially around the edges of the pan.

Cool slightly: letting the onions lose some heat before mixing them with the sour cream and eggs helps keep the filling smooth.

Balance the filling

Cream and eggs: sour cream adds tang and richness, while the eggs help the filling set as it bakes. Whisk them together with the nutmeg, salt and pepper before adding the onions.

Crisp bacon: frying the lardons in a dry pan renders their fat and gives them a browned finish. Drain them on kitchen paper so excess fat does not make the filling greasy.

Check for doneness

Set centre: after 30 to 35 minutes at 200°C, the filling should look firm rather than liquid in the middle. The top should be golden and the pastry edges lightly crisp.

Resting time: leave the tart for 10 minutes before cutting. This gives the filling time to settle and makes neater slices.

Serve it simply

Fresh salad: a crisp green salad is an optional side that brings a fresh contrast to the rich, savoury tart. Dress it lightly so it does not compete with the onion filling.

Warm slices: serve the tart warm after its short rest. It works well as a main dish for lunch or supper.

Recipe notes & tips

• Slice the onions into thin, even rings so they cook at a similar rate.
• Keep the onions over a low heat and stir regularly to prevent browning too quickly.
• Let the onions cool slightly before adding them to the sour-cream mixture.
• Flour the work surface lightly so the dough rolls out without sticking.
• Use the set centre and golden top as cues alongside the stated baking time.
• Rest the tart for the full 10 minutes before slicing.

Variations

• Extra herbs: stir chopped chives into the sour-cream mixture for a fresh savoury note.
• Caraway: add a small pinch of caraway to the filling for a traditional-seeming aromatic twist.
• Cheese topping: scatter a little grated cheese over the filling before baking for a more savoury crust.
• Meat-free: leave out the bacon and season the onion filling well with salt and pepper.
• More pepper: add extra freshly ground black pepper to give the creamy filling a sharper edge.

Common mistakes to avoid

• Rushing the onions: they may stay firm; cook them gently for the full 25 to 30 minutes.
• Scorching the onions: high heat can make them brown before softening; lower the heat and stir regularly.
• Adding hot onions: they can make the filling harder to mix smoothly; let them cool slightly first.
• Stretching the dough: thin spots may tear in the tin; roll it wide enough and press it into place gently.
• Cutting too soon: the filling may slump; rest the tart for 10 minutes before slicing.
• Overbaking: the filling can become dry; take the tart out once it is golden and set.

How to store

Cool leftovers, cover or place in an airtight container, and refrigerate for up to 3 days. Reheat slices in an oven until warmed through; the base may soften slightly after storage.

Frequently asked questions