The other day I was cooking some kind of Asian dish, maybe Malaysian or Indonesian, and it called for lemon juice. I didn't have the lemon juice handy, so I re-constituted some tamarind paste and used that. I figured the lemon juice was used for its sour taste, not specifically its citric qualities.
Anyone have any comments on this? The dish tasted OK, and as far as I can see, tamarind is also used to import sourness.