Crush black pepper and cumin into coarse stage in pestle. Keep this aside.

Heat oil in kadai add mustard to splutter. Once done add sliced onion, sliced green chilli to this. Saute until onion changes thin colour. Add curry leaves to this.

Peel the skin of raw banana and make this to cubes and add to the kadai. Don't cube the raw banana before, as it turn black. If you are cutting the raw banana before soak in buttermilk.

Mix salt in quarter cup of water and keep it. Sprinkle salt water little in raw banana close with lid and cook for 15 sec. Open the lid add crushed cumin and black pepper powder. Again sprinkle water and close with lid. Let it cook for another 1 minute in low flame. If you cook in high flame it will get burn. Do this process repeatedly until banana cook half.

When banana cooked 50 % add turmeric powder, chilli powder, garam masala, coriander powder and fennel powder. Sprinkle remaining salt water close with lid and cook.

When it almost done open the lid and cook until it done 100%. Banana should be little moisture and it should not be dry either saughy. Switch off the flame.

Raw banana stir fry is ready to serve. You can serve this with any variety rice. I am serving with coconut rice.