Hi Maple!
I don't find that spicy food has any different effect on my BG than any other food and when I cook a hot curry I work out the carbs and jab accordingly - but I cannot tolerate rice or naan, I just can't seem to get the correct dose at the correct time for those foods and spike all over the place when I try. However, whenI eat in an Indian restaurant, I find it very difficult, becaue they often use a lot of sugar in their curry sauces (which I don't when I cook curry). So, you might be having seriously more carbs than you think? If it's the same restaurant you use all the time, it might be worth phoning, explaining the issue to them and asking if they do put sugar in the vindaloo - I'm sure they'll tell you.
Also, don't forget they tend to use lots of onion and tomato as the base, so maybe you're underestimating your insulin needs?
Smidge