Pour the almond and powdered sugar mixture into a large bowl, then add the egg white in batches. Knead the paste well after each addition to obtain a homogeneous texture.
Knead carefully before adding more egg white to prevent the paste from becoming too soft. If you knead it properly, you'll obtain a very supple, fine-textured paste without needing to add more liquid.
Note: Knead for about ten minutes. It will become more malleable and elastic, allowing you to stretch it very thinly without it tearing.