Rinse the pigeon pea lentils and pressure cook it adding required water until mushy. Meanwhile in a pan add oil, red chillies, chickpea lentils and black gram lentils. Saute for a minute and then include coriander, cumin and fenugreek seeds. Saute till they get roasted well. Switch off once done. Finally include grated coconut and curry leaves. Coconut and curry leaves warm up by the heat of pan.
In a mixer add the roasted spices from above step and grind it to coarse paste adding water as needed. Keep the cooked pigen pea lentil ready.
Next heat a vessel adding chopped cabbage, potato, turmeric powder, jaggery, tamarind extract and some water. Let the veggies cook till soft. You can include some salt for the veggies to absorb now. Next include spice paste prepared from above step and cooked pigeon pea lentils. Combine everything well. Adjust consistency by adding water. Check salt and adjust that too. Bring the curry to boil and swich off.
Heat a seasoning pan with all the seasoning ingredients, as the mustard sizzle transfer it to curry. Cabbage potato curry is ready to serve.