Rinse white peas well under running water and soak them for atleast 8 hours to overnight. Later drain the water and give a good rinse.
Heat oil in a cooker and add ginger, garlic and green chilies. If using Instant pot, follow the same steps on the saute mode.
Saute them until aromatic for about 1 minute. Then add hing, peas, salt, turmeric, red chilli powder and garam masala.
Saute for 1 minute & pour water. Mix well.
Pressure cook on a medium heat for 6 whistles. If using Instant pot, press pressure cook button and set the timer to 11 minutes.
When the pressure releases completely, open the lid and check if the peas are done. They should be soft cooked & not al dente. If they are undercooked, pressure cook for a little longer.
Take 3 to 4 tbsps cooked peas to a small bowl and mash them very well. Then add back to the ragda so it turns thick.
Add tamarind & jaggery (or 1 to 2 tbsps sweet tamarind chutney). Mix well and taste test. If you want you can also add more garam masala & salt at this stage.
Simmer ragda for a few more minutes until it turns thicker. Turn off when it is of pouring consistency as it thickens a bit after cooling.
How to make Patties
Boil potatoes in a pot or pressure cooker just until fork tender. Do not over cook them. I boiled the potatoes along with the white peas in the instant pot for 11 minutes. (check my step-by-step photos above for more details)
Peel the potatoes while still hot or warm. Crumble or mash them well and cool completely. Then add chaat masala, ginger, green chili, salt, coriander leaves & 4 to 6 tbsps bread crumbs (or poha powder).
Mix all of them and taste test. Add more salt if needed. The mixture must be non-sticky. If it is sticky then add more bread crumbs or poha powder.
Divide the dough to 8 portions and make balls. Then flatten them. If you want to make them extra crisp, roll the pattice in poha powder and press down so it sticks to the patties.
Heat 1 tablespoon oil in a non-stick pan and spread it. When the oil becomes hot, place the patties and fry them on a medium high flame.
When the base turns golden and crisp, invert them and fry until golden. Set these aside.
Assemble Ragda Patties
Assemble only when you are ready to eat else the patties become soft.
Pour 2 ladles of ragda to a serving plate. Pour 1 tablespoon of sweet tamarind chutney & some green chutney. Then place the patties on it.
Top with all the 3 chutneys as much as you want. Then sprinkle coriander leaves, onions and tomatoes.
Sprinkle some sev and chaat masala. Serve immediately.