1. Preheat the oven to 400°F (200°C). Line a 12-cup muffin pan with paper liners. Sift the flour, baking powder, baking soda, and salt into a large bowl. Stir in the sugar and poppy seeds, making a well in the center.

2. In a separate bowl, beat the eggs. Stir in the sour cream, butter, oil, and lemon zest. Add to the flour mixture and stir until just mixed. Divide the batter among the muffin cups, filling each one three–quarters full.

3. Bake the muffins for 20 minutes, or until golden brown and a toothpick inserted in the center comes out clean. Remove the muffins from the pan, and transfer to a wire rack to cool. Sift confectioner's sugar over the tops while still warm.