Take two bowls. In the first bowl, combine the flour, sugar, baking powder, salt, lemon zest, and poppy seeds. Mix together with a spatula.
In the second bowl, mix the yogurt, eggs, vanilla extract, and sunflower oil. Whisk these wet ingredients into the bowl with the flour mixture.
Use a spatula to gently mix until you have a smooth batter. Once the dry ingredients are incorporated, stop mixing.
Pour the batter into a loaf pan lined with parchment paper and bake at 345°F (175°C) for 50-55 minutes, until done.
Once the cake has cooled, make the glaze by mixing 3 tablespoons lemon juice with 150 grams (1¼ cups) powdered sugar. The glaze should be thick but pourable. Add more lemon juice or powdered sugar if needed.
Pour the glaze over the cake and let it set before slicing.
How to store
Wrap the cake in aluminum foil; it will keep well at room temperature for 4-5 days.