Preheat your oven to 350°F (175°C). Grease a 9×5-inch loaf pan with butter or nonstick spray, or line it with parchment paper for easier cleanup and loaf removal.

In a large bowl, whisk together the flour, baking powder, baking soda, and salt. This ensures your leavening agents are well incorporated and prevents uneven rising.

In a separate mixing bowl, combine the sugar, melted butter, beaten eggs, vanilla extract, lemon zest, and lemon juice. Mix until smooth. The lemon gives the loaf its refreshing zing, while the butter and eggs provide richness and structure.

Gradually add the dry ingredients to the wet mixture and stir gently until just combined. Avoid overmixing to keep the texture light and tender. Gently fold in the finely chopped rhubarb.

Pour the batter into the prepared loaf pan and smooth out the top. Bake for 50 to 60 minutes, or until a toothpick inserted in the center comes out clean. If the top begins to brown too quickly, loosely cover it with aluminum foil around the 40-minute mark.

While the loaf cools, prepare the glaze by mixing the powdered sugar with lemon juice until smooth. You can adjust the lemon juice to get your desired thickness—use less for a thicker glaze or more for a light drizzle.

Once the loaf has cooled in the pan for about 10 to 15 minutes, transfer it to a wire rack to cool completely. Drizzle the glaze over the top and finish with a sprinkle of lemon zest for a burst of citrus flavor and color.