Trial and error? Personally I generally like the same things from the Chinese/Indian etc. I use the same takeaway too. I just guess this time and adjust for next time. Like everything we don’t cook ourselves or doesn’t have a packet it’s a bit of a lottery in my opinion, if you want that sort of food, you just have to accept bad numbers afterward. (Just my uneducated opinion). I hope you find a perfect way to enjoy your prawn toast