Soak one cup of moong in water for four to five hours, or overnight. After draining the water, rinse the dal.
In a pot, add the soaked moong dal and enough water to cover it. Boil until the dal is soft but not mushy (about 10-15 minutes). Drain excess water and let it cool.
In a mixing bowl, combine the boiled moong dal with finely chopped onions, tomatoes, green chillies and coriander leaves. Add salt, chaat masala and lemon juice to taste.
For extra texture and flavour, mix it with some chopped raw mango or sev.
Plate the moong dal chaat and garnish with additional sev, coriander leaves and a squeeze of lemon. Enjoy your fresh and tangy snack.