In a bowl, sift the flour with the baking powder. Beat the sugar with the oil using an electric mixer. Add the lemon juice and grated zest, then the yogurt. Gradually incorporate the flour with the baking powder.

Gently fold in the egg whites beaten to stiff peaks with a pinch of salt, moving from bottom to top. Finally, add the candied citron cubes. Transfer the mixture to a greased and floured pan.

Bake in a preheated static oven at 350°F (180°C) for about 40-50 minutes. Always do the toothpick test to check if the cake is done. Let cool and sprinkle with powdered sugar.