Preheat your oven to 350°F (175°C) and prepare a 9x5-inch loaf pan by lining it with parchment paper.

In a large mixing bowl, cream together 3/4 cup of softened butter and 1 1/4 cups of sugar for about 2-3 minutes until light and fluffy.

Beat in 2 large eggs, one at a time, ensuring each is fully incorporated before adding the next.

Stir in 1/3 cup of sour cream, 1 1/2 tablespoons of lemon zest, and 1 1/2 teaspoons of vanilla essence until just combined.

In a separate bowl, whisk together 1 3/4 cups of flour, 1 tablespoon of baking powder, 1/2 teaspoon of salt, and 1/4 teaspoon of ground cardamom.

Toss 1 3/4 cups of diced rhubarb in the dry mixture until well-coated, reserving a few slices for garnish.

Gently fold the dry ingredients into the wet mixture until just combined, being careful not to overmix.

Pour the batter into the prepared loaf pan and arrange the reserved rhubarb slices on top.

Sprinkle a tablespoon of sugar on top and bake for 55-65 minutes, checking for doneness with a toothpick.

Let the bread cool in the pan for about 10 minutes before lifting it out and cooling completely on a wire rack.