Preheat your oven to 350°F. Grease a 9x5-inch loaf pan or line it with parchment paper.

Bring the butter, eggs, and sour cream (or yogurt) to room temperature for best texture.

Chop the rhubarb into small pieces. If using frozen rhubarb, thaw it completely and drain off any excess liquid.

Zest the lemon, taking care to only grate the bright outer rind and avoid the bitter white pith.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.

In a large bowl, beat the softened butter and sugar together until light, fluffy, and pale.

Add the eggs one at a time, beating well after each addition.

Mix in the lemon juice, lemon zest, sour cream (or yogurt), and vanilla until just combined.

Gradually add the dry flour mixture to the wet ingredients, stirring gently until no streaks of flour remain. Avoid overmixing.

Fold the chopped rhubarb into the batter gently to distribute it evenly.

Pour the batter into the prepared loaf pan and smooth the top with a spatula.

Bake for 50 to 60 minutes. Check at 50 minutes by inserting a toothpick into the center; it should come out clean or with a few moist crumbs.

Let the bread cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely before glazing.

To make the glaze, whisk together the powdered sugar and 1 to 2 tablespoons of fresh lemon juice until smooth and pourable. Adjust thickness as needed.

Drizzle the glaze over the completely cooled loaf and let it set before slicing.