Gently stir the cool liquid into the large bowl with the flour mixture. I would recommend adding in a quarter of the liquid at a time and stirring until uniform before adding more in.
Stir the batter for a few minutes. It will initially feel quite stiff but should loosen up after about one minute. Keep stirring until only a few small lumps of flour remain.
Place a fine mesh strainer over a second bowl and pour the batter mixture through the mesh. This step helps to remove any leftover lumps in the batter.
Lightly grease a 20 cm round cake pan and pour the batter in. Hold the cake pan and tap it gently on the kitchen bench to get rid of air bubbles. Then cover with aluminium foil.
Place your steaming rack inside a large wok and fill with water until 1 cm below the top of the rack.
Cover wok with lid and bring to the boil. Once the water is boiling, carefully place the cake on the rack and cover with lid again. Lower the head to medium and steam the cake for up to one hour. Halfway through, add more water to replace what has evaporated.
To test if the cake is cooked, insert a chopstick into its centre and dig out some of the cake. It should look brown and slightly translucent. If cake is ready, place a jujube over the centre to decorate (and cover the hole).
Once the Gato Lasir is cooked, let it cool on the kitchen bench overnight. The following morning, wrap it in foil and transfer to the fridge.
Notes
Don't use a toothpick to test if the cake is ready. The reason for this is because it might still come out clean even if the cake isn't fully cooked yet.
Kansui adds a bit of depth to the colour of the cake. However, if you can't find it at your local shops, you can bypass the ingredient. Overall, this shouldn't affect the flavour.