Soak the chana dal for 4-5 hrs. Drain and blend to a smooth paste.
Heat oil in a pan. When the oil is smoking hot, add 1/2 tsp cumin seeds and 1 chopped green chilli. Once they start to splutter, add 1 tsp of ginger paste and a pinch of salt. Fry for a minute or so and then add the dal paste.
Saute for a few minutes, add salt, a pinch of sugar and little turmeric. Mix well. Keep cooking on a low flame till the dal paste starts to leave the sides of the pan. Take care that the dal doesn't stick to the bottom of the vessel.
Add in the bhaja masala, the scraped coconut and the raisins and mix well and adjust the seasonings. Keep aside.
Shave the parwal using a kitchen peeler, chop both the ends, about half an inch or so. Gently scoop out the insides of the parwal from one side using the bottom of a spoon, taking care that the parwal 'pocket' remains intact and is not ruptured, as in the picture. Heat oil and shallow fry the parwal 'pockets' till light brown. Keep aside and allow to cool.
Now gently fill all the parwals with the dal stuffing. Keep aside.
For the gravy, heat 1 tbsp oil, add the shahi jeera and allow to splutter. Add the tomato paste, ginger paste, turmeric powder, coriander powder and red chilli powder and cook over medium heat till the oil starts to separate from the masala.
Add 1/2 cup of warm water, salt and sugar to taste and bring to a gentle simmer.
Stir in the sesame paste, throw in the green chillies and mix thoroughly; gently place the stuffed parwals in the gravy and cook over a low flame for a further 5 odd minutes.
Add a dollop of ghee, sprinkle garam masala powder and serve hot with plain rice.