Originally an Eastern Moravian dish, this tart can be topped with any filling you fancy.

Method:

• In a small bowl, stir together the yeast and warm milk with a pinch of the sugar. Leave somewhere warm for 5–10 minutes until bubbles have formed on the surface.
• Sift the flour into the bowl of a stand mixer fitted with a dough hook attachment. Add the remaining sugar, salt, lemon zest, butter and egg yolk (save the egg white for later). Pour in the yeast mixture and mix on medium speed for 8–10 minutes until the dough has come away from the sides of the bowl and is smooth and slightly shiny.
• Cover with a tea towel or cling film (plastic wrap) and leave the dough to rise somewhere warm for about an hour until it has doubled in size.
• While the dough is rising, make the filling. Heat the blueberries in a frying pan over a high heat, along with the sugar and lemon juice. Bubble away for about 10 minutes until the berries have broken down and the liquid has reduced by half. Transfer to a bowl to cool slightly.
• To make the rum butter streusel, combine the flour, sugar and butter in a bowl and rub together with the tips of your fingers until the mixture resembles breadcrumbs. Drizzle the rum over the top and give it a quick stir with a spoon. Set aside.
• Preheat the oven to 160°C (325°F) fan and line a large baking tray with baking parchment.
• Once the dough has risen, lightly dust the work surface with flour and roll out the dough to a circle about 30cm (12 inches) in diameter. Place the dough circle on the prepared baking tray and then spoon the filling evenly over the top, leaving a 1cm (½-inch) border around the edge of the dough. Leave to prove for a further 20–30 minutes, so the border rises slightly and helps contain the filling, then scatter the streusel topping over the blueberries.
• Brush the edges of the pastry with the reserved egg white, then bake the tart for 18–20 minutes until the edges have gone a lovely nutty-brown colour.
• Leave to cool slightly on the tray before cutting into eight pieces and serving. Best eaten on the day of baking. If you want to serve it the next day, warm in the oven to revive the dough.

Extracted from My Bohemian Kitchen (Murdoch Books)