Hi All, first post despite lurking for a while! 

I use Tamarind concentrate in a prawn curry that's very basic, ie not many ingredients. It calls for four tbsp of tamarind juice, I have cut this back to two tbsp of concentrate and still found that I needed to increase the jaggery to just offset the 'tartness' of the tamarind a little. But I agree that tamarind is just great as a souring agent and adds a much better 'flavour' than either lemon juice or amchur (mango) powder.

Just felt the need to point out that you may need to experiment with the quantities when using the concentrate, or you may find the curry just too sour.

ATB

Max