Bring eggs, butter, sour cream, and milk to room temperature before mixing to ensure proper emulsification and create a tender, moist crumb that won't be dense.

Always zest the lemon before cutting it in half to juice, as it's much easier to zest a whole firm lemon and ensures you capture maximum aromatic oils for superior lemon flavor.

Mix the wet and dry ingredients until just combined—overmixing develops gluten and results in tough, dense doughnuts instead of the delicate, tender texture you're aiming for.

Use a piping bag fitted with a round tip to fill your doughnut pans evenly, ensuring consistent baking times and preventing over or underfilled doughnuts that bake unevenly.

Allow doughnuts to cool for 5-10 minutes in the pan before dipping in glaze—this creates a slight crust that helps the icing adhere better without sliding off or becoming too thin.