Heat oil in a pan. Add potatoes, salt and a little water. Mix well and add dabeli masala, lemon juice, half cup of sweet tamarind chutney and sugar. Mix and cook till the moisture is absorbed. Transfer the mixture into a plate and spread it. Sprinkle masala moongphali, coconut, pomegranate pearls, black grapes, half the sev and coriander leaves over the top. Slit the pavs horizontally without cutting through. Spread red chilli-garlic chutney, a layer of the stuffing, sweet date and tamarind chutney, onion and sev in between the two halves. Place the stuffed pavs on a hot tawa. Press slightly and toast on both sides, with a little butter, till done. Serve hot.