Berry Lattice Pie

Combine all ingredients for the sponge, cover, and let sit until a foamy cap forms

Cover the berries with sugar and let the juices drain off

Add salt, eggs, mix well, and gradually incorporate the flour, followed by both types of butter

Knead the dough and leave it in a warm place for 1 hour

Once risen, punch it down and let it rest for another 30 minutes

For the filling, whisk together the egg and sour cream

Divide the dough, setting 1/3 aside; roll out the larger portion and place it into a buttered baking dish

Spread the sour cream filling and berries over the crust

Roll out the remaining dough and weave a lattice crust on top

Brush with egg