Place ginger, garlic and green chilies in a food processor. Process to a smooth paste. Set aside.
Place ginger-garlic-chili paste, coriander (cilantro) leaves, chickpea flour, rice flour, baking soda and white sesame seeds in a large bowl. Season with salt. Add water little by little to make smooth batter.
Pour batter into a greased plate or container.Sprinkle with black sesame seeds.
Transfer to a steamer, and cook for 15-18 minutes. Leave to cool. Cut into cubes. Remove from plate. Set aside.
Meanwhile heat oil in a frying pan over medium heat. Arrange the coriander cakes in a single layer in the pan. When one side is brown and crispy, flip over to brown the other side. Remove from pan. Drain on paper towel.
Serve immediately.