Place flour in a large bowl, add salt and mix.
Cut cold margarine into the flour.
Rub in the margarine with your fingers, fork, knife or pastry cutter, until the mixture resembles large breadcrumbs.
Add 1 cup cold water and knead, adding the rest of the water as needed.
Knead to form a soft, smooth, pliable and elastic dough. (A food mixer can also be used.)
Flatten dough to form a disc and put in a plastic wrap, this helps it chill faster.
Put in the refrigerator to chill and relax for three hours or more.
Allow dough to warm up a bit before rolling. If frozen, defrost in the refrigerator possibly overnight.
Meanwhile, prepare the pasty filling and set aside.
To roll dough: Press dough lightly with the rolling pin at the centre and roll outwards.
Roll in one direction a couple of times then lift it up and rotate a quarter turn and roll. Keep rolling and rotating till you get your desired thickness. Be patient and take your time. If the dough is getting sticky, lift it up, sprinkle flour on the countertop, the rolling pin and lightly on top of the dough.
Cut into 8-inch circles using a small plate or whatever is available.
Place meat and vegetables in the middle of the pastry, leaving enough space around for sealing. (Place a small knob of butter on top of the filling if you used lean or not well-marbled meat.)
Bring the two sides of the dough together in the middle and crimp them to seal well. (You can also, put your filling on one side of the dough.)
Bring the empty side over the filling to cover it, crimp the edges together.
Place on lined baking sheets.
Beat egg with 1 teaspoon of water or milk, glaze the pasties.
Bake at 180 deg. C for 50-60 minutes until golden.
Serve your Nigerian Cornish Pasty with tea and a green salad or coleslaw or Zobo and a drizzle of ketchup or any drink of your choice.