Heat the oven to 350°F (175°C). Grease an 8 1/2 x 4 1/2-inch or 9 x 5-inch loaf pan and line it with parchment, leaving an overhang on the long sides.

Whisk the flour, baking powder, and fine salt together in a medium bowl. Set the dry mixture aside.

Rub the finely grated zest of two lemons into the granulated sugar with your fingers until the sugar feels slightly moist and smells strongly of lemon.

Whisk the eggs and lemon sugar until smooth. Add the neutral oil, Greek yogurt or sour cream, freshly squeezed lemon juice, and vanilla extract, then whisk until combined.

Fold the dry ingredients into the wet mixture just until no dry flour remains. Avoid overmixing so the finished loaf stays tender.

Transfer the batter to the prepared pan and smooth the top. Bake for 50 to 60 minutes, beginning to check at 50 minutes, until golden and a skewer inserted in the center comes out clean or with a few moist crumbs.

Cool the loaf in the pan for about 15 minutes, then use the parchment overhang to lift it onto a rack. Let it cool completely, for about 1 hour total cooling time, before glazing.

Mix the confectioners' sugar with 1 1/2 to 2 tablespoons of fresh lemon juice until thick but pourable. Drizzle the glaze over the cooled loaf and let it settle before slicing.