Substitue for Palm Vinegar for Indian Chicken dish needed

For the Chicken Vindaloo recipe, if you replace the Palm Vinegar with some Apple Cider Vinegar, and then add about a quarter tsp of cane sugar, you should get a very similar effect. The Palm vinegar is generally a little sweet and citrussy, so this should balance it out. The vinegar would essentially evaporate in the vindaloo leaving behind the flavour you need.

I hope you find a more firsthand response, but this might help. I was curious and found this at chowhound: 'Supposedly, it has a bit of a citrusy taste and [...] recipe uses some lime zest to try to replicate the citrus (while using white wine vinegar.)