Take raw bananas, cottage cheese, carrots, green chillies, raisins, 1 tsp turmeric powder, garlic, 1 tsp ginger, salt and coriander powder in a bowl and mix well. Divide them into equal portions and shape them into balls. Put them into the preheated air fryer and cook for 15 minutes.
Meanwhile to make the gravy, put tomatoes, onions, cashewnuts, remaining turmeric powder, red chilli powder, remaining ginger and salt in a mixer jar and grind into a puree.
Heat olive oil in a non-stick pan, add cumin seeds and fenugreek seeds and saute till fragrant.
Add the puree, sugar and milk and bring it to boil. Reduce heat and cook till the mixture is well cooked and smooth.
Transfer the gravy into a serving bowl, add the koftas and serve hot.