Soak the dry white peas or vatana for a minimum of 8 hours or overnight
Drain, transfer to a pressure cooker pan or pot and add enough fresh water to cover it completely by 1/2 an inch. Add turmeric powder and chilli powder to this and mix well
Pressure cook for 15 mins or 4-5 whistles. The peas need to get really soft and mushy
Let pressure release naturally and take out the cooked peas. Use the back of a spoon or potato masher to mash it. Don't mash completely, let some texture remain in the peas. Set this aside
Grind the green chillies and ginger together in a small mixie or pestle and mortar. You can also chop them up really fine
Heat oil in a pan add cumin seeds and asafoetida
When the cumin seeds sizzle and turn a shade darker, add the chilli-ginger mixture
Add the cooked mashed pas and salt. Mix well.
Adjust water to bring it to the right consistency. You want the ragda to flow easily from your spoon but not be water.
Bring to boil, simmer for a minute, and then remove from heat
Serve hot with chapati or ragda patties and chaat chutneys