In a saucepan, combine the chicken with all the above mentioned ingredients "for cooking chicken". Cook covered till the chicken has cooked well and turns light brown. Using a wooden spoon, slightly mash the cooked chicken. Keep aside.
Heat a non-stick pan, add oil, let it turn hot.
Add, onions chopped small, a few pinches of salt, saute till translucent.
Add ginger-garlic paste and green chili, saute till onions turn brown in color.
Add the cooked chicken to the onions, stir fry for a few minutes.
Have a taste, add more salt or chili powder/ground pepper for spice if needed.
Add cilantro, cook for a minute, remove the pan from the heat, keep aside.
In a large bowl, combine flour, salt and add water little by little as you knead the dough. Add water till you get a soft and smooth dough. Knead for a few minutes.
Make 8 balls out of the kneaded dough.
Place one of the balls on a wooden board or a clean surface, sprinkle some flour over the dough, using a rolling pin roll the dough to a thin round shape. Repeat with other dough balls.
Heat a non-stick pan over low heat, place the rolled dough onto the pan, slightly warm up the rolled dough for a few seconds, don't let it cook.
This is not to cook the dough it's just to warm it up. Remove from the pan.
Make a paste using 1 tbsp flour and with 1½ tbsp water.
Using a knife, cut the warmed up rolled dough into 2 halves.
Make a cone shape out of one of the halves, spread the flour paste along the edges of the cone and seal it.
Add the chicken filling into the cone, don't over stuff it.
To close the cone, spread the flour paste on the edges and glue it together.
In a small bowl, beat an egg well.
Using a pastry brush, spread the beaten egg over the unfried samosa dough. This is just optional.
Heat enough oil to deep fry in a frying pan, place the stuffed dough into the oil. It should be submerged in the oil.
Fry till the samosas turn golden brown in color.
Transfer to a kitchen paper towel.
Seve warm along with tomato ketchup or chili sauce.