Beat the eggs with a pinch of salt using a mixer in a deep bowl. Add the baking soda to the yoghurt and stir. Once activated, add it to the eggs.
Add the oil and continue beating. Sift the flour and pour the baking powder to it. Gradually, spoon by spoon, add the floury mixture to the other mixture and stir. Do not add it all at once.
Crumble the feta cheese and add it as well. Stir everything with a spoon only. Oil the muffin nests in the muffin tray. Sprinkle them with flour.
Using a spoon, pour equal amounts of the mixture into each muffin nest. Preheat the oven to 302°F (150 °C) shortly before putting them in it. Put them inside and raise the heat to 356°F (180 °C).