Preheat the oven to 175°C. Wash the beets and bake them with a pinch of salt in a piece of aluminum foil till they become soft and juicy (around 50min.). Then cool them down and peel them gently. Place peeled beets in a big bowl and mash them with a fork till the paste becomes quite smooth. Add the raisins, feta cheese cut into cubes, olive oil and spices. Mix it all together well, cover with a plate and place in the fridge.
Now make the dough. Sieve the flour and baking powder through a strainer. Add salt and sugar. Make a small hole in the flour and fill it with egg yolks, melted butter and warm (not hot!) water. Knead the dough till it becomes smooth and elastic. Then divide the dough into 25-30 small balls.
Preheat the oven to 180-190°C. Take a flat baking tray and line it with a piece of baking paper. Each ball should be rolled out in a round flat shape (with a diameter of 10-12cm). Place the filling in the middle of each circle and close it with help of water (put a bit of water with your fingers in between the dough edges just before joining them together). Use a metal fork or a wooden stick to decorate the empanadas edges. Cover the tops of dumplings with the egg white and decorate them with some seeds like for instance sesame or linseed. Bake the empanadas in portions of 8-10 till they become golden brown. When ready, place them on a big plate and let them cool down a bit.
To make the sauce just mix all the ingredients together and season it according to your family needs. It will take just a minute.