Hi Judy,
Sorry, I forgot to mention that my "sinking sponge" uses a recipe without emulsifier and without oiling the cake tin.

SPONGE100 g flour 1/4 tsp baking powder 1/4 tsp vanilla
5 yolks 60 g sugar 1/4 tsp salt
20 g/1 tbsp honey
50 g oil 50 g water
5 egg whited 60 g sugar 1/4 tsp tartar

1. Sieve the flour, baking powder, and vanilla powder.
2. Whisk the yolks, salt, honey, and sugar by hand until the sugar has melted. Add oil
Stir to mix well.
4. Fold flour into this mixture.
5. Beat the egg white, sugar and tartar until firm.
6. Fold half the white into the yolk mixture.
7. Fold in the remaining white.
8. Pour into an ungreased 9" round tin and bake at 150 C for 40 mins.
9. Invert tin over netting and leave to cool.

Took a baking class from a Taiwanese lady named Cnastance in S'pore.

Oh, you may want to write to Betsy again for my e-mail address. She has it now.

Best
Yong