Soak the red beans and chickpeas in water overnight. Next day, soak the black lentils for 1/2 hour and then combine all the lentils together. If you like, you can also add in some orange masoor dal as well as chana dal.
Cook all the soaked lentils in a pressure cooker for about 2 whistles and 10 minutes on slow until they are almost cooked. Do not overcook as they will still cook when the other ingredients are being incorporated and you risk making them mushy.
Soak the tamarind ball in hot water and squeeze out all the pulp
Separately, fry the finely chopped onions until light brown. Add the garlic-cumin-green chillies paste, turmeric powder, black pepper powder, red chilli powder, sambhar masala and salt as per taste. Fry the masala well and then add finely chopped mint. Stir fry for a minute and leave aside.
In a deep saucepan, bring the lentils to a slow boil, and add the spinach, amaranth (chawli) and dill. If you like, add the fenugreek (methi) now as well.
Once the leaves start softening add the tamarind pulp and the fried onion spice mix. Add water (or stock), if required, and bring to a boil.
Once the whole mixture comes to a boil, sprinkle chopped Meer which is cut in shape of noodles.
Keep stirring the Osh while sprinkling the meer to avoid it being sucked to the bottom of the vessel.
Keep stirring with a gentle hand till the Meer is cooked (around 5-7 min).
Tasty yummy Osh-e-Meer is ready. Garnish with the hung curd, fried onion and coriander if you wish to. Serve hot with crusty bread in deep plates.