Dissolve the yeast in 2/5 cup (100 ml) cool water, along with the sugar and 3 tbsp flour. Leave it to bubble.
Sift the flour, add the salt, break in 2 eggs, add the yeast and remaining water. Knead a soft dough, leave it to rise until doubled in volume.
Once it's risen, divide it into balls, use oil to help you shape them. Stretch them out, put crumbled feta cheese and a little butter in the middle of each.
Fold the edges inward and place the buns in an oiled oven dish. Leave them for another 40 min.
Whip the 2 eggs with the finely crumbled feta cheese and stir well. Pour this mixture over the buns.
Bake at 356°F (180 °C). Once they're ready, sprinkle them lightly with water and cover with a towel, so they soften.