This is the recipe that I have used since my teenage days.
4 cups (120) self-raising flour
4 cups (180g) sugar
1 orange (rind and juice) for 1 1/2 cups(100ml)or
mixture of coconut milk and pandan juice(100ml)
1/2 tsp baking powder
1/2 tsp cream of tartar
40 ml cooking oil
pinch of salt.
* The cup is the size of 1/3cup.
Separate egg whites from yolks, beat egg whites with half of the
sugar and cream of tartar till stiff.Mix egg yolks with the remainder
half of the sugar, Add in the orange juice and rind,mix well.
Follow by the oil. Finally blend in the flour (sifted with baking
powder). Fold in the beaten egg whites into the egg yolks mixture,
mix well. Pour into the sponge cake baking tin and bake in
preheated oven for 35 minuted at180 degrees Celsius.
When cake is baked, remove from the oven and immediately turn it
up side down to cool.