Peel the skin of green plantains and cut them into small even sized cubes (You may keep the peels if you like, as they are edible).
Heat 2 tablespoons of coconut oil in a large thick bottomed pan and add mustard seeds.
When mustard seeds splutter, add the broken dry red chilies and curry leaves, fry for a few seconds.
Add the chopped green bananas to the pan, add enough salt and lightly fry for about a minute in low heat.
You shouldn't stir the green bananas at this point, as they tend to stick because of the texture. It is very much fine if they stick to the pan at this point, as it is natural, and it will change as it gets cooked. Make sure you keep the heat low at this time.
Add the water to the pan and as the mixture starts boiling, close the pan with lid and cook the green plantains for about 6 minutes or until the plantains are cooked.
Meanwhile coarsely grind together the coconut and cumin seeds (without adding water), you can use a food processor for this. If you are using shredded coconut, you can skip the grinding and directly add the shredded coconut and cumin powder (instead of cumin seeds).
As the green plantains are cooked, gently toss the cooked green plantains using a good spatula. If the plantains appear to be still sticky to the bottom of the pan, it may be because they are not yet cooked. Lightly sticking to the pan is fine, but when you use a good quality spatula to toss them, they will easily come off the pan once they are cooked enough. In case the green bananas are not cooked enough and if there is no water left in the pan, you may add a little more water and then cover and cook for few more minutes. If you add too much water or if you cook for too much time than needed, the plantains will crumble and become mushy in texture.
Add the grind coconut mixture to the cooked green plantain bananas, add the turmeric powder and red chili powder and add the remaining 1 tablespoon of coconut oil. Gently stir the contents using the spatula and cover the pan and cook the contents for another 2 more minutes.
After 2 minutes of cooking, open the pan and stir the contents gently so everything will be blended nicely.
Green plantains with coconut and spices is now ready to serve, enjoy it hot with rice for lunch or dinner!