To prepare tangy green water for Gol Gappa, blend one cup of mint leaves, coriander, a small amount of white salt, chaat masala, roasted cumin, black salt, a pinch of asafoetida (hing), half cup of tamarind chutney, and four green chillies in a mixer. Then mix this green chutney in ice-cold water. You can adjust the tanginess as per your preference.