Line a 20cm bamboo steaming basket with grease-proof paper.
Whisk eggs, ovalette and castor sugar together until light and creamy. Sift in flour and double action baking powder and mix lightly with a metal spoon until well combined.
Add the orange juice gradually and stir in orange rind. Mix into a batter. Pour the batter into prepared bamboo basket. Lightly level the surface of the batter with a spatula. Steam over rapidly boiling water for 15-20 minutes or until the cake is done. Leave the cake to cool completely before cutting into slices.