I use a 2L/3Litre Pressure cooker for this recipe. Add 3 tbsp of water to it,
Next goes in the chopped onions. Layer them to cover the surface. I generally use about half the quantity of onion to that of potatoes but it is upto you. You can reduce or increase the quantity or even completely skip the onion in this recipe.
Next top the onions with the chopped potatoes. For this post I have peeled the potatoes, but if you don't mind the skin, keep it on. I generally keep the skin on especially if using the golden potato variety. When using russet potatoes, I peel it since my family does not care of the bits that come to their mouths while eating esp in Poori masala.
Add the spices along with salt right on top. We do not want it to touch the bottom to avoid the spices burning. Finish it with cilantro and curry leaves.
Set the timer. Cook on high for 2 whistles or around 5 minutes. Whichever is earlier.
Ensure your pressure is built around 2 min mark (the safety valve will stop jiggling and protrude). My first whistle came at around 3:52 minutes and second one at 4:06 minutes.
Important Tip: If you find that your whistles are not starting even around 4 minute mark, check to see if you pressure valve is built up. If it's not and/or it is but whistles are not coming, remove and check to see if the pressure is not leaking on the sides. Need to check your casket in that case.
Let the pressure settle. You can also release pressure manually (be careful and use a spoon to avoid scalding your hands). I let it settle instead of doing it manually.
While that's resting, heat remaining oil and temper the ingredients given under that section. Add the mustard seeds and when it pops, add the rest and saute until the lentils are slightly browned. Set aside.
Open the pressure cooker.
and mash the ingredients lightly.
Add enough (lukewarm/boiling) water as per your liking. You can also, if needed, thicken it up by adding the besan paste and heating it slightly until it reaches your desired consistency.
Add the tempered ingredients
along with freshly squeezed lemon juice.