Lemon juice, Tamarind, Kokum, Amchur powder are usually added for the sour flavour and sweetness is afforded by sugar, jaggery etc. The sweetness kills the sharp tangy edge of the sour ingredient even as the same lemon makes a sweet dish wonderfully memorable.
Obviously our food habits mirror Life in general as if brings both sweet and sour moments. Moments that we cannot avoid moments that make life the beautiful journey that it is. This is aptly captured in an old Hindi movie called Khatta Meetha directed by Basu Chatterjee (http://en.wikipedia.org/wiki/Khatta_Meetha_%281978_film%29). Do watch it if you get an opportunity to do so.
This is the essence of my blog, to capture both sweet and sour moments that happening around us! Then ofcourse there is Teekha (Spicy), moments that test our very patience and bring out the true nature of our character, that force us to sit up and think.. How can we ignore those?