Rinse and soak rajma for 8 hours in lot of water. Discard the water and rinse them well. Pour 2 cups fresh water.
Cook them in a pot or pressure cook until soft but not mushy.
Regular pressure cooker - cook directly in the pressure cooker for 4 whistles on a medium flame. For pot-in-pot method, pressure cook for 6 whistles.
Instant pot - pressure cook on high pressure for 18 to 20 mins. Wait for the pressure to release naturally. (refer notes)
If done correctly, the rajma must be soft when you bite into it. It should not be al dente or even slightly hard. They must hold their shape yet & not become mushy. When you mash the rajma it must be soft.
If it is hard or al dente, pressure cook for 2 more whistles.
Onion tomato puree
You can skip this step if you want to use chopped onions but onion puree gives a smooth curry. To make the puree, add cubed onions to 2 cups of hot water and boil for 3 mins until transparent. Drain the water. Cool them and make a fine paste. Set this aside.
In the same blender jar puree tomatoes. [ I also blend 2 tbsps of cooked rajma with the tomatoes to get a thicker & flavorful gravy.]
How to make rajma
Heat a pan with oil and saute cumin & bay leaf until they sizzle.
Turn the flame to low, saute ginger garlic paste until a nice aroma comes out.
Add onion paste and saute until it turns golden.
Saute tomato puree until the raw smell vanishes.
Add all the spice powders and salt. Saute until the mixture turns thick & the masala begins to smell good.
Then transfer cooked rajma to the masala along with rajma cooked water.(stock)
Pour half cup water and stir. Add ginger juliennes and slit green chili.
Mix well. Cover & simmer on a low flame for 10 to 15 mins.
Check if rajma are done completely. When you mash the rajma it must be soft.
Sprinkle crushed kasuri methi & stir. Add coriander leaves. Taste test and add more salt if needed.
To get a restaurant style taste, pour 2 tbsp cream. Turn off the stove.
Serve rajma with chawal (rice), onion and lemon wedges.