Onion Tart Recipe: Classic and Hearty for Federweißer Season

Onion tart is baked with a simple yeast dough and a topping of soured cream and egg: slice the onions into rings, cook them until soft, stir them into the topping, spread it over the dough and bake for 35 minutes. Allow around two hours in total – only a good half hour of that is hands-on, the rest is down to the yeast and the oven.

September is the season for all this: onions from the new harvest have just gone into storage and are still beautifully juicy, and in wine country, the Federweißer (new wine) season is just beginning. That pairing is no accident – it's one of the oldest autumn traditions there is: young, still-fermenting wine alongside a warm, hearty tart. If you'd rather skip the alcohol, cloudy grape juice works just as well.

Ingredients

Serves 4 (one 26cm springform tin):

• 250g plain flour
• 1/2 cube fresh yeast (about 21g)
• 125ml lukewarm milk
• 30g soft butter
• 1 tsp sugar
• 1 tsp salt
• 1kg onions
• 100g streaky bacon (optional)
• 1 tbsp butter, for frying
• 200g soured cream
• 2 eggs
• 1 tbsp flour
• 1 tsp whole caraway seeds
• Salt and pepper from the mill

Method

1. Dissolve the yeast in the lukewarm milk with the sugar and leave for 10 minutes. Knead the flour, salt, butter and yeast milk into a smooth dough, then cover and leave to rise for 45 minutes, until it's visibly bigger.
2. Meanwhile, peel the onions, halve them and slice into thin strips. If you're using bacon, dice it finely too.
3. Melt the butter in a large frying pan, render the bacon briefly, then add the onions. Cook gently over a medium heat for 15 minutes, until soft and translucent but without taking on any colour. Take off the heat and let cool.
4. Whisk the soured cream, eggs and flour together, then stir in the cooled onions. Season with caraway, salt and plenty of freshly ground pepper from the Salt and Pepper Mill – the topping can be seasoned quite boldly, as it mellows in the oven.
5. Preheat the oven to 200°C (conventional). Roll out the dough, lay it in the greased springform tin and press up an edge about 3cm high.
6. Spread the onion mixture evenly over the base and bake the tart on the middle shelf for 35 to 40 minutes, until the topping has set and the surface is flecked with gold.
7. Let it rest in the tin for 10 minutes, then cut into slices with the Bread Knife. Its serrated edge cuts cleanly through the crisp rim without crushing the soft topping. Serve warm.

kjøk Tip

Make sure the onion mixture has cooled before you stir in the eggs – otherwise they'll start to cook, and the topping turns flecked instead of creamy. And grind the pepper fresh: whole peppercorns keep their essential oils sealed in, while ready-ground pepper from a packet has lost most of that within a few weeks. You'll find more ideas for savoury baking in our Baking range. To look after your tools: keep mills stored dry and away from the hob, so no steam gets into the mechanism – damp salt makes it clog. Wash the bread knife by hand and dry it straight away; it doesn't belong in the dishwasher. A serrated edge stays sharp for a long time, but should eventually be professionally resharpened rather than run over a household sharpener. Wash olive wood handles briefly by hand, dry them well, and rub them with a little cooking oil now and then.

FAQs

Can I prepare the onion tart ahead?

Yes. The yeast dough can be made the day before and left to rise overnight in the fridge – which actually gives it more flavour. The cooked onions will also keep for a day in the fridge; just mix the topping shortly before baking.

Why does my base sometimes turn out soggy?

Because the onions still hold too much liquid. Cook them until most of the water has evaporated, and add the tablespoon of flour to the topping – it reliably binds the rest.

Does the recipe work without bacon?

Easily. Just leave the bacon out and cook the onions in butter or oil instead. For a bit more depth, stir in a teaspoon of smoked paprika or a few strips of sautéed smoked tofu.