Cut the heart over the fat layer.

Discard the upper part.

If the heart has a membrane - remove it by pulling it off the heart.

Wash the exposed heart chambers under running water. When the water fills the chambers, you will feel the heart swallows a bit.

Press and squeeze the heart with your fingers. This action will push the water and clotted blood out of the heart chambers. Repeat the process few times until the heart is completely clean.

Repeat this process until all the hearts are cleaned.

Take a skewer and impale the heart through the aorta - the blood vessel in the center of the heart.

Push the skewer until it comes out of the tip of the heart. Push the heart down the skewer and impale another heart.

Fill the skewers with hearts but don't forget to leave some space at the bottom of the skewer.