Preheat the oven to 350°F (175°C). Grease and flour a 9x5-inch loaf pan or line it with parchment paper.
Mix the dry ingredients: In a medium bowl, sift together the flour, baking powder, and salt.
Combine the wet ingredients: In a large bowl, whisk together the lemon zest, lemon juice, and sugar until smooth. Add the eggs and whisk well. Stir in the oil or melted butter. Combine the wet and dry ingredients: Gradually fold the dry ingredients into the wet mixture, stirring until just combined. Avoid overmixing.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake for 50-60 minutes, or until a toothpick inserted into the center of the bread comes out clean.
Cool in the pan for 10 minutes, then remove the bread and transfer to a wire rack to cool completely.
Optional glaze: For extra sweetness, whisk together powdered sugar and lemon juice until smooth, then drizzle over the cooled bread.