First soak raw kala chana in 4 cups of water overnight.
After they are soaked prepare for tempering. Heat oil in a kadhai. To this add cumin seeds. Once cumin seeds start crackling add soaked kala chana. Sprinkle red chili powder and mix well. Cook this on medium heat for 5 minutes. After 5 minutes switch off the heat and let it cool down. Meanwhile, chop cucumber, tomato, capsicum, onion, raw mango and green chili.
In a mixing bowl add chopped cucumber, tomato, raw mango, capsicum, corn, onion and green chili. Mix this well.
Now add half cooked kala chana to the mixing bowl. Combine this mixture very well.
In a bowl mix all ingredients together for dressing and pour it over the mixture. Combine well.
Adjust salt as per taste.
Serve this kala chana salad or black chickpea salad immediately.