Preheat your oven to 375°F (190°C) and prepare a muffin tin with paper liners.

Combine granulated sugar with lemon zest in a mixing bowl, rubbing the zest into the sugar until fragrant.

Add sour cream, vegetable oil, melted butter, eggs, vanilla extract, and fresh lemon juice to the sugar-zest mixture. Whisk until smooth.

Sift the all-purpose flour, baking powder, baking soda, and salt over the wet mixture, folding gently until no flour streaks remain.

Fold in the poppy seeds until evenly distributed.

Scoop the batter into the muffin tin, filling each cup to the top.

Bake for 16–22 minutes, or until the tops are golden brown and a toothpick comes out clean.

Allow the muffins to cool in the pan for 5 minutes, then transfer to a wire rack.

In a small bowl, whisk together powdered sugar and lemon juice until smooth to create the glaze.

Drizzle the glaze over warm muffins and allow it to set before serving.