a squirt of Lemon dressing [/quote]
I have used many things to sour hot curries, lemon juice; lime juice; various vinigars, and more recently tinned tomarto juice or some of the 'blitzed' contents of tinned toms, added late in the cooking. The latter works best for me. However one of my local BIR's madras (not a fantastic BIR, but perfectly OK), had a flavour that I recognised but for ages I couldn't 'place' After weeks of wraking my brains I finaly realized it was sweet lemon dressing: that discusting overly sweet sh*t you get on pancakes at fairgrounds and craft fairs and the like. It tastes vile on these because it's designed both to sweeten AND add a lemon flavour, and for some reason the vendors of these pancakes find it necessary to use loads of sugar AND this sauce, rather than using sugar and lemon juice which would be just great thanks!
Anyway, the point of the above diatribe, apart from slating pancake vendors, was to suggest that this rather sickly stuff does work RATHER well in a madras, providing other forms of sweetner (tom puree for example), are reduced.
My local BIR uses it with good rresults; I was interested to see it's use suggested here, because I've been meaning to try it for ages!