In a wide pan, heat oil. Add urad dal, mustard seeds and cumin seeds. Once they start to sizzle, add red chilli and a pinch of hing. Add chopped onions and a pinch of salt to cook them faster, until they become translucent. Then add ginger garlic paste and give a good mix. Cook for 2 mins and then add green chillies and curry leaves. Season with turmeric and salt. Add cubed plantain. Give it a gentle toss. On low-medium flame, cook for about 4 minutes for the flavors to combine. Finally add grated coconut and cook for 5 more minutes. Turn off heat. Serve with rice or roti.