Soak the tamarind in some water and set aside.
Directly roast the lone large onion directly on the gas on a slow flame till it turns black all over. Keep turning it so it gets roasted on all sides. An easy way to do this is to stick a fork into the onion so it becomes easy to keep turning it. When done, remove the blackened cover and chop into large pieces.
Similarly, roast the Dry coconut (copra) piece directly on the gas till it blackens all over. Scrape off the blackened portion slightly after it cools down – not completely though. The blackened portion adds to the taste. Then pound the copra piece well. (In kokani or marathi, this is called ‘thechaney’). Alternately, you can chop into fine pieces too
In a ‘tadka ladle’ (called ‘pali’ in kokani/marathi) or on any flat pan/tawa – add 1 tspn oil, the lavang (cloves), dalchini (cinnamon), black pepper and dhaney (coriander seeds) and roast well. Basically the dhaney have to get roasted well till they slightly change colour. Turned off the gas, then add the khus khus and mix well. The reason why the khus khus is added after the gas is turned off is because, otherwise, the khus khus gets burnt. Wait till this mix cools down.
Grind this along with the roasted onion, roasted copra and fresh grated coconut into a fine paste. The trick is to first run the mixie with these ingredients as is for one round, then add a little water and run it again. The resultant paste should be thick (not watery) and fine. Keep aside
In a pan, in 2-3 tspns of heated oil, add the pounded garlic pods, hing (asafoetida), haldi, finely chopped onions and salt (note that Tisrya are a salty seafood – so you need hardly about 3/4th tspn of salt for this quantum of Tisrya). Roast till the onion gets a little soft. Then add the large chopped pieces of potato and the cleaned Tisrya (look below for how they are cleaned and one side of the shell removed) – and add water (Note: Use the water in which the Tisrya have been first warmed – see the prepping process described below). The water has to be just enough so that it is level with the Potato+Tisrya volume – roughly the same volume. To this, add the garam masala and red chilly powder. Cover with a flat lid and add some water ON the lid. Cook over a medium flame till the onion & potatoes get cooked. The Tisrya get done in the meantime. To check if the onion is cooked, take a small bit out and press. If it is soft and disintegrates easily, it means the onion is done. The whole process should take about 10-15 minutes for this quantum of Tisrya.
Once the onions and potatoes are cooked, add the tamarind pulp and boil well for a full five minutes – till the raw smell of the tamarind goes away.
Turn down the flame to low and add the ground masala and blend well. Add water if you want the gravy to be a little more ‘liquidy’. Basically, how thick or liquidy the gravy has to be is an individual preference – so you can decide. Bring the gravy to a light boil on the low flame. And your Tisrya are done.