Rising and proofing time:
1 1⁄2–21⁄2 hrs

Special equipment:
10 x 13in (26 x 32cm) rimmed baking sheet

Ingredients:
4 tsp quick-rise dried yeast
3 tbsp olive oil, plus extra for greasing
3 1⁄4 cups bread flour, plus extra for dusting
1 tsp salt

For the filling:
4 tbsp unsalted butter
2 tbsp olive oil
1lb 5oz (600g) onions, finely sliced
1⁄2 tsp caraway seeds
sea salt
freshly ground black pepper
1⁄2 cup sour cream
1⁄2 cup crème fraîche
3 large eggs
1 tbsp all-purpose flour
3oz (75g) bacon, cooked and crumbled

Method:
1 To make the crust, dissolve the yeast in 1 cup warm water. Add the olive oil and set aside. Sift the flour and salt into a large bowl. Make a well in the middle of the flour mixture and pour in the liquid ingredients, stirring all the time. Use your hands to bring the mixture together to form a soft dough. Turn it out onto a well-floured work surface and knead for 10 minutes, until soft, smooth, and elastic.

2 Place the dough in a large, lightly oiled bowl, cover with plastic wrap, and leave to rise in a warm place for 1–2 hours, until doubled in size.

3 To make the filling, heat the butter and olive oil in a large, heavy saucepan. Put in the onions and caraway seeds, and season well with salt and pepper. Cook gently for about 20 minutes, covered, until they are soft but not brown. Remove the lid and cook for another 5 minutes until any excess water evaporates.

4 In a separate bowl, whisk together the sour cream, crème fraîche, eggs, and flour, and season well. Mix in the cooked onions and set aside to cool.

5 When the dough has risen well, turn it out onto a floured work surface and push it down gently with your knuckles to knock it back. Lightly oil the baking sheet. Roll the dough out to roughly the size of the sheet and line the sheet with it, making sure the pie has an upturned edge. Use your fingers to ease the dough into position, if necessary. Cover with lightly oiled plastic wrap and leave to rise in a warm place for another 30 minutes until puffy in places.

6 Preheat the oven to 400°F (200°C). Gently push down the dough if it has risen too much around the edges of the sheet. Spread the filling out over the pie base and sprinkle the top with bacon.

7 Place the baking sheet on the top rack of the oven and bake for 35–40 minutes until golden brown. Remove from the oven and leave to cool for at least 5 minutes before serving. Serve warm or cold.

PREPARE AHEAD:
Cover and chill overnight.

BAKER’S TIP:
This delicious onion and sour cream tart looks like a cross between a pizza and a tart, and is indeed made with a traditional pizza dough base. It is not much known outside its native country, but is well worth making. It was traditionally served during grape harvesting time in parts of Germany.

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