Kecap manis, or Indonesian sweetened soy sauce, can be substituted for the Thai sweet soy sauce. If you can't find bird's-eye chillies, substitute another small, hot chilli, such as serrano.

Thai Sweet Potato Soup Recipe: This soup combines wholesome sweet potatoes with creamy ... Pour in the vegetable broth and coconut milk. Add the soy sauce and stir to combine all the ingredients well.