Peel and grate the ginger, and also grate jaggery. Add water to tamarind and boil it till tamarind becomes soft.
Take a kadai add 2 tbs oil and fry the grated ginger for few minutes or till it changes colour to light brown.
Then grind together garlic, ginger, turmeric, jaggery, chilli powder, salt and tamarind pulp into a fine thick paste don't add water, grind it with tamarind pulp.
Heat a kadai and add 10 tbs of oil to it. Now add mustard seeds, chanadal as well as urad dal, and when the mustard seeds splutter add the ground paste to it and fry for a few seconds. This pickle goes well with idlis, dosas, and also with rice.