Preheat the oven to 350°F.
Grease a 9x5 inch loaf pan with butter and dust it lightly with flour.
Sift the flour, baking powder, and salt into a large mixing bowl.
In a separate bowl, whisk the eggs, sugar, and vanilla extract until creamy.
Add the sunflower oil and Greek yogurt to the egg-sugar mixture. Mix well.
Stir in the zest and juice of two lemons. Then, add the wet ingredients to the dry. Mix until smooth.
Pour the batter into the loaf pan and smooth the top.
Bake for 40 minutes. Insert a wooden skewer or fork into the center of the loaf; once it comes out clean, the pastry is ready.
Remove the loaf from the oven, let it cool in the pan for 10 minutes, and then invert it onto a wire rack to cool completely.
Meanwhile, for the glaze, mix the powdered sugar with 2 tablespoons of lemon juice and 1 teaspoon of zest from the third lemon.
Pour the glaze evenly over the cooled loaf and sprinkle with the remaining lemon zest. Let the glaze set before slicing and serving.
