Blueberry and raspberry tart

Ingredients

For the dough

• 125 g butter
• 220-240 g flour
• 1 small egg
• 1 tablespoon sugar
• 15 ml lemon juice
• 30 ml cold water
• 1/2 teaspoon baking soda
• 1 g salt
• 1 teaspoon grated lemon zest

For the filling

• 150 ml raspberries
• 300 ml blueberries
• 1 tablespoon butter
• 4 tablespoons sugar
• 8 g cornstarch
• 8 g vanilla sugar

Preparation

1. Cream 125 g soft butter with 1 tablespoon sugar and the salt. Lightly beat the egg and mix it with the baking soda dissolved in 15 ml lemon juice. 2. Work in half the flour, then the rest, along with the grated lemon zest, and knead briefly. Gradually add up to 30 ml cold water if the dough needs it, stopping when it comes together into a nonsticky ball. Cover and chill for at least 60 minutes. 3. In a double-bottomed saucepan, caramelize 2 tablespoons sugar for about 3 minutes, until amber-colored. Stir in 1 tablespoon butter. 4. Add the raspberries and blueberries along with the remaining 2 tablespoons sugar. Boil for 3 minutes, then add the cornstarch mixed with 1 tablespoon cold water and the vanilla sugar. Cook for 1 more minute, until the filling thickens slightly. 5. Heat the oven to 180°C. Set aside a small piece of dough for decoration and roll out the rest on a floured work surface, into a sheet slightly larger than a 23 cm pan. Place it in a pan greased with a little butter, press the dough a few centimeters up the sides and prick it with a fork. 6. Bake the empty crust for 8 minutes, until it looks slightly dry on the surface. Take the pan out, add the filling and decorate with the reserved dough, cut into shapes or strips. 7. Bake the tart for another 25 minutes, until the crust is golden. Let it cool a little before slicing.