I've named this vibrantly flavored mango-tamarind broth "magical" after the main character in Chitra Banerjee Divakaruni's novel, Mistress of Spices. She is described as a priestess of the magical powers of spices. One taste of the complex spice blend in this rasam and you'll be a believer. A rasam is a savory sweet-sour-spicy broth that is served in Indian cooking like an aperitif, to stimulate the appetite. I recently learned how to make a pineapple based version of this from the dynamic Chef Suvir Saran, and was hypnotized at first taste. The combination of flavors, from the sweet fruit, sour tamarind, fiery chiles and fragrant curry leaves literally explodes in the mouth. The spices include asafetida, which is not only a complex flavor enhancer, but also has medicinal properties as a digestive aid and as a possible treatment against the H1N1 flu virus. I liked the fruitiness of Suvir's pineapple version and imagined that mango would make a good substitute. I used prepared mango pulp for its smoothness in this broth; canned versions are widely available in Indian grocers. If you cannot find canned mango pulp, you can make your own by boiling a peeled mango, pureeing and then straining it. —Beautiful, Memorable Food
Prepare the rasam spice blend: place dried chiles, cumin seeds, coriander seeds, and peppercorns in a spice grinder and grind into a coarse powder.
Dissolve the tamarind concentrate in the hot water. Stir until it is all dissolved. Pour this into a medium saucepan and add the spice blend, mango pulp, cilantro, and salt. Stir, bring to a boil, and reduce to a simmer.
Make a tempering oil (this is where the magic happens!): pour oil into a small frying pan, add the mustard seeds and green chiles, and warm over medium heat for a few minutes, until the mustard seeds begin to pop. Then add the curry leaves and asafetida, stir until combined, and remove from heat. Add the cayenne pepper and stir again. Add the finished oil to the soup. Serve hot or warm, with additional cilantro for garnish.