Preheat oven to 350°F (175°C). Grease and line a loaf pan.
Whisk dry ingredients. In another bowl, beat eggs, butter, sour cream, lemon juice, zest, and vanilla.
Optional: Add poppy seeds to the wet mix.
Combine wet and dry ingredients, avoiding overmixing.
Pour batter into pan and bake for 50-60 mins.
Cool for 10 mins, then transfer to a wire rack to cool completely.
Slice and serve. Store leftovers in an airtight container.
