Preheat oven to 350°F (175°C). Grease and flour a standard 9x5 inch loaf pan, or line with parchment paper.

Toss the chopped rhubarb with 1 tablespoon of sugar in a small bowl and set aside. This lightly coats the rhubarb and helps prevent bleeding into the batter.

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

In a large bowl, cream together the softened butter and 1 cup of sugar until light and fluffy (about 3 minutes). Beat in the eggs one at a time, mixing well after each addition.

Mix in the Greek yogurt (or sour cream), lemon juice, and lemon zest until just combined. Gradually beat in the dry ingredients until no streaks of flour remain. Do not overmix.

Gently fold in the coated rhubarb pieces until evenly distributed throughout the batter. Pour the batter into the prepared loaf pan.

Bake for 50 to 60 minutes, or until a wooden skewer inserted into the center comes out clean. If the top browns too quickly, loosely tent with foil after 30 minutes.

Let the loaf cool in the pan for 15 minutes before carefully turning it out onto a wire rack to cool completely.

To make the glaze, whisk together the powdered sugar and 2 tablespoons of lemon juice until smooth. Drizzle generously over the cooled loaf before slicing and serving.