This is a very easy with minimal ingredients.
Remove the seed from the plum and chop them finely.
In a heavy bottom kadai/pan, heat gingely oil and add mustard and hing. After it splutters add the plums and saute.
Once the plums are half cooked, add salt,chilli powder and saute them nicely in a medium heat.
When the plums are coming together i.e they shd not stick to the pan ( surula varumbothu). Add the jaggerry and mix well.
Cook till the oil floats on top. Remove from fire and cool and store in an air tight container.
Serve with idli/ dosai. But best served with Thayir Satham/Curd Rice...:)