Wash the amla and soak in salted water for 15 minutes. Drain, wash and dry thoroughly with a cotton cloth.
Place tamarind in a vessel and cover with water about 1 inch over the level of tamarind. Simmer for 10-15 minutes until the tamarind is soft. After checking there are no seeds, grind it to a paste and keep aside.
Dry roast the mustard and methi (fenugreek) seeds separately until aromatic. Grind separately into powders and keep aside.
Heat half-litre sesame oil in a large frying pan. Once the oil is hot, reduce the flame to medium and deep-fry the whole amlas in batches until golden brown(colour of a potato) on the outside. This will take around 5-7 minutes per batch. Drain with a wire or mesh ladle and keep aside.
In the remaining oil in the pan, fry all the ingredients for the tempering. Turn off the flame and add half the asafoetida. Mix these dry ingredients well.
To this, add the prepared tamarind paste and mix well and add the fried amla. Now add in ½ cup grated jaggery. Once the amla is well coated with the spice paste and the oil has cooled sufficiently, transfer the oil along with the tempering to this vessel. Mix all the ingredients gently but thoroughly, using hands, so that everything gets mixed well and amla doesn’t get crushed.