Boil the potatoes. Peel and smash the potatoes. Take 1 cup of water and add jaggery and kokum to make sweet and sour chutney and allow it to boil. Strain and keep it aside. Now heat a pan add oil and the sour and sweet chutney, bring to a boil.
Now add the smashed potatoes, red chilli powder and salt. Mix well. Remove the mixture in a plate. Chop the onions and coriander leaves. Keep the masala singhdana also aside.
Now take a tawa, heat it, take pav add butter and sweet and sour chutney, the potatoes mixture, onions, and masala singhdana. Cover it and apply butter.
And let it be done on both sides till crispy. Then garnish with sev and masala singhdana.
