Peel off Shallots , wash & fry until pale in a pan with little bit oil.
Do the same for green chilies & papaya. (Papaya must cut in to small strips about 1 inch size).
Add these 3 ingredients together in a plastic bowl & add some salt, 1/2 cup vinegar & mustard powder. Mix well.
Put the piece of banana leaf in the bottom of Clay chatty or glass vessel.
Stack above mixture on that leaf & add the rest of vinegar.
Close tightly with a plastic wrap. (Do not use aluminum foil)
Set aside up to 5-6 days.Just role over the content once per day.Then it is ready to use.