for dough:
take maida, oil, salt and kalonji seeds in a bowl, mix well.
add water and make a firm dough.
cover it with a wet cloth and let it set for 5 minutes.
for stuffing:
heat oil in pan.
add cumin seeds and ginger-garlic-green chilli paste.
stir and cook for a minute on medium flame.
add onion and saute until golden brown.
now add boiled green peas and stir fry for a minute.
add red chilli powder, turmeric powder, coriander powder, garam masala powder and dry mango powder, mix well.
add mashed potatoes and salt, mix them properly and cook for 2-3 minutes.
add coriander leaves and switch off the flame.
transfer the stuffing to a bowl and let it cool for a while.
to make samosa:
pinch a medium sized ball from the dough and make a roti.
cut it into square shape and divide into equal strips.
take out all the strips in a plate.
now take another piece of dough and repeat the same process.
cut it in square shape and divide into equal strips.
slide even strips downward and apply water on front strips and paste a strip over it.
press it so that it stick well.
apply water over it and stick downward stirps over it.
repeat it again and again and make it like chatai.
cut it in round shape and remove sides.
now cut it into two semi-circles.
spread water on edges and give it a cone shape by folding it from both sides (overlapping one side over another) and pressing them to seal the sides.
put some filling in the cone.
apply water on the edges and press it tightly with thumb and index finger to seal them.
make all samosas in same way.
heat oil in a kadai on medium flame.
when oil is medium hot, add 3-4 samosas in it and reduce the flame to low.
deep fry them until golden brown.
tranfer them to a plate and serve with tomato ketchup.