- Cook the soaked black chickpeas with salt till done. Drain and set aside. 
- Lightly peel the raw bananas - keep some skin on. Chop into cubes. Wash and drain. 
- Remove the skin of the yam and chop into cubes. Wash well and drain. 
- Combine raw banana, yam, green chilli, turmeric powder, red chilli powder and salt in a pressure cooker. Add 3/4 cup water and cook till done. The vegetables should be well cooked and really soft.  
- Add the drained chickpeas, jaggery and black pepper and mix. Add water if needed. Keep on simmer for around 15 minutes, stirring occasionally. Adjust seasoning.  
- Grind the coconut and cumin to a coarse mixture. Add into the kottu curry and mix. Cook for another five minutes. Switch off. 
- In a fry pan, heat the coconut oil. Splutter the mustard seeds. 
- Fry the red chillies, curry leaves and coconut till the coconut turns golden brown.  
- Pour onto the top and close the lid. Mix at the time of serving.