Wash the rice with the water until the water looks white. Drain the rice and put the water in a pot. Use the rice for other thing.
Boil this water, then get 3 litre out if it. If it's not enough, add hot water until it gets 3 litre.
Stir in the salt and sugar until they're dissolved. Transfer to a container. Let it cool down to room temperature.
Rince the bokchoy until clean (no dirt in between the inside stem). Cut them half if they're big.
Arrange the bokchoy into the water.
Put the weight on it so that all the bokchoy are completely submerged in the water. I used a mortar as the weight.
Close the container. Leave at room temperature for 6 days.
After 6 days, drain bokchoy. Rinse with clean water. Store in a closed container in the refrigerator. They can also be put in a container per serving then freeze it.
