Peel and dice the plantain.
Bring 3 cups water to a boil with turmeric and salt. Add diced plantain to this and simmer for 6-7 minutes until the plantain is nearly cooked. Keep a watch on this as different varieties may have different cooking times. This should not turn into a mush. Drain in a colander and keep aside.
Meanwhile, in a small mixer jar, grind the red chillies, shallots and garlic to a coarse paste.
In a pan, heat coconut oil. Add mustard seeds. Once it splutters, add the curry leaves and stir for few seconds.
Add the ground paste and stir on high flame for 1-2 minutes.
Add the cooked plantain to this and toss gently until coated with spices.
Garnish with fresh coconut and serve hot with rice and Kerala Sambar.