SEM AUR ALOO KI SABJI (INDIAN BROAD BEAN AND POTATO CURRY)

This recipe is from one of my Bihari friend but i made little changes she used fresh ground white mustard paste i could'nt find white mustard here so I have some Dijon mustard paste in hand which iam using for salad s so i used that one, there is not much difference in the taste.
Sem ki phalli ---- 1/4 kg (250 gms) Chikkudukayalu, Indian broad beans
Potato ---- 1 big
Onion --- 1 big
Tomato --- 1 medium
Mustard paste --- 1 tea sp
Red chilli powder --- 1 tea sp
Turmeric powder ---- 1/2 tea sp
Mustard seeds -- 1/2 tea sp
Ajwain ---- 1/2 tea sp
Methi seeds --- 1/4 tea sp
Kalonji --- 1/2 tea sp
cumin seeds --- 1/2 tea sp
Oil ----- 1 tab sp (in the original recipe they use mustard oil for this if you dont like you can replace with any other oil you like but mustard oil will give a authentic taste.
METHOD:----
Remove the string from the sides of sem(Indian broad beans) slit, open and break them in to 1 inch pieces.
Peel,wash and cut potato in to 1/2 inch pieces,peel wash and chop onion very finely and chop tomato in to small pieces.
Heat oil in a pressure cooker and add mustard and let them popup then add cumin seeds,kalonji,ajwain, and then methi seeds now add chopped onion and fry till onion become soft then add chopped tomato and cook till it also become soft then add mustard paste,red chilli powder, turmeric powder mix well and cook till oil comes out from the sides.
Now add potato pieces and sem pieces and salt to taste add 1 cup water mix well and cover and cook for 2 whistles and remove from heat and let it cool.
then open and serve hot with rice or roti