Mix the yoghurt with the baking soda and stir until effervescent. Stir the eggs and mix them with the yoghurt.
Melt the butter and add it to the yoghurt and eggs, along with the sugar. Stir until homogeneous.
Add 2/3 of the coconut flakes. Add the flour and stir a soft dough.
Shape balls and roll them in a mixture of the sugar and the remaining coconut flakes.
But them in a baking tray, covered with baking paper.
Bake about 20 min. at 428°F (220 °C)