For the dough we will need these products:egg, sugar, flour, kefir, butter, vanilla, soda, baking powder and salt. Sift the flour with salt, baking soda and baking powder into a deep bowl and mix. With a whisk, beat the egg with the yogurt and sugar. Add the liquid kefir-egg mixture to the flour. Mix well with a spoon or whisk. Pour in the melted butter.