Thoroughly whisk rice flour, wheat starch, cornflour together. Add salt, oil and 300 millilitres room temperature water, continue to whisk.
Add 400 millilitres boiling water. Whisk again. Cook over medium-low heat till just thick enough to coat sides of pot thinly, stirring constantly. Place pot in water-bath. Stir till half-cool. Not shown in video.
Bring steamer to a boil. Place perforated tray in steamer. Arrange moulds, measuring 6 x 2 centimetres, slightly apart on tray. Fill moulds with batter to 3 millimetres from edge. Cover and bring steamer back to a boil.
Steam 20 minutes over rapidly boiling water. Uncover. Cakes should have some water on top. If there is, steam uncovered till water evaporates, 1-2 minutes. Remove cakes from steamer.
Cakes should be mushy just after steaming. Leave to cool down and set. Resteam just before serving if you prefer hot/warm chwee kueh. If batter is overthickened before steaming, cakes may be set or half-set whilst piping hot.
Rinse chai poh twice. Drain in sieve, pressing to remove excess water. Transfer to mixing bowl. Add garlic and mix thoroughly.
Heat wok till hot. Place chai poh mixture in wok. Add enough oil to almost cover mixture, about 120 millilitres.
Fry over medium-high heat till garlic is golden brown. Add soy sauce and reduce heat to low.
Add sugar and stir till dissolved. Turn off heat. Taste and if necessary adjust seasoning.
Unmould chwee kueh and top with fried chai poh, along with some oil. Add sambal on the side if you like your chwee kueh spicy.