Cut the banana into two and put it in boiling water with skin and cook for five to seven minutes. Take it out and peel the skin. Cool it. Then you can grate it or gently mash it by hand.
Chop the onion and green chilli.
In a kadai put the oil and when it is hot add mustard. When it pops up add urad dhal and fry till it become light brown. Add chopped onion, green chilly, curry leaves and fry well. Add the aniseeds crushed. Stir for a while. Add banana gratings, salt, turmeric powder and sambar podi and mix well. Close with a lid and keep it in low flame for four to five minutes. Finally add the coconut gratings and stir everything well. Add lemon juice and remove from stove.
Note: If you do not like sombu smell, then you can omit it and add a pinch of asafotida powder.