Many thanks ;o)
I'm sure Panfusine will have a better answer, but I've used ground dried lemon rinds and it has not caused any harm! It puckers less than real amchur, but it works.
Thanks, nogaga!! Wondering if perhaps sumac would work . . . or maybe tamarind? ;o)
anardana powder (dried pomegranate powder), or even blended up fresh raw green mangoes. Tamarind paste can be a tad too strong (in dire circumstances, I've fallen back on tamarind coupled with brown sugar to offset the pucker inducing tartness)
The sumac question is excellent, AntoniaJames. I feel that its sourness would be too different from the amchur sourness, but I can't quite put my finger on why that is. Yet I am certain it is true. The amchur, maybe, has that raw fruitiness, whereas sumac, in my mind, has a more salty characteristic. But who knows... What did you try?