I've lived in Thailand for 15 years and have never tried an orange cake from a cafe. I have tried the ones sold in 7 11, but they don't taste good. As for my favourite Thai cake, it would have to be the khanom luk tan. It is a traditional Thai dessert that has a texture similar to a cake. You should try it when you come back to Thailand.
Hi Che, so SP acts as an emulsifier and I believe it is optional. She used it to make the cake more stable and to emulsify the ingredients better. Keep in mind, we were baking in Thailand, the flour will be different and act different because of heat and humidity than for example in parts of Europe or America. If you really wish to substitute it, a website I found stated the following options: Transglutaminase (TGase), Plant protein, Hydrocolloids, Maple fiber. 😊
