Growing up in Chennai, South India, one of my earliest memories is of my mother feeding me rasam, a peppery soup with a flavour of asafoetida and curry leaves, and rice, with a dollop of ghee (clarified butter).A piquant mix of flavours with tamarind extract, tomatoes, spices and sometimes lentils, a bowl of rasam is seen as comfort food across the South Indian states of Tamil Nadu, Andhra Pradesh (where it is calle chaaru), Karnataka (where it is referred to as saaru) and Kerala.Given its long…