To make the tamarind chutney, take 100 gm tamarind and 100 gm jaggery (break into small pieces and then add) in a pan and boil it for 5 mins on a medium flame with 1/2 cup water. Stir it continuously to avoid burns. Cool and transfer into a mixer jar and grind it once so that the tamarind seeds do not get grounded but only the pulp gets loose. Strain it and rub the remaining pulp on the strainer while adding little water. Taste and add sugar if needed then add black salt, salt, roasted cumin powder and red chilli powder according to taste. Then boil this and you can also add water if consistency is too thick. Cool it and store in the refrigerator for 5-6 days.
To make the green chutney, add all the ingredients in a mixer jar, except the lemon juice and salt. Grind it well by adding little water in between. Transfer it n a bowl, add lemon juice , salt and black salt, mix it well.
Next, dry roast all the ingredients listed under the dabeli masala. Then let it cool and grind them together.
Heat a kadhai. Add oil, when the oil is heated add green chilli, mash the boiled potatoes and add it. Mix well. Add 1 tsp of black salt, 2 tbsp dabeli masala , 1 tsp amchoor powder and salt according to taste. Stir well and cook for 5 mins.
Now add 3 tbsp tamarind chutney mixture, then add 1/2 cup of water. Mix well and turn off the flame.
Spread this potato mixture in a flat bowl, spread the peanuts, coriander leaves and pomegranate seeds over it.
Take the bun, cut it into half, cook it on the tawa from both sides with butter. Spread the garlic chutney on one side and tamarind chutney on other side. Then spread the potato mixture, add the chopped onions and fine sev .Place the other half on it and serve.