Rub the shrimp with sake and salt, and let it sit for 5 minutes.

Thinly slice the onion and soak it in water for 5 minutes, then drain. Remove the strings from the snap peas and cut them diagonally in half.

Bring a pot of water to a boil. Add the snap peas and boil for about 30 seconds, then transfer them to cold water and drain. In the same pot, boil the shrimp for about 2 minutes, then remove and let cool.