Prepare the dough: Sift together the flour, salt and baking powder in a medium mixing bowl. Using a wooden spoon, stir in the oil or shortening and enough warm water to make a sticky ball.
Knead the dough for 3 - 4 minutes until smooth and elastic. Add more flour if the dough is too sticky to handle, but it's better to be sticky rather than dry.
Knead until smooth but still sticky.
Cover the dough with the bowl and leave to rest for at least 30 minutes.
Prepare the filling: Boil the potatoes in water until tender, drain and mash with a fork. Add butter or margarine and milk to make a soft mixture.
Mash until smooth. Don't blend in the food processor!
Season well with garlic powder, cumin, salt and pepper. Set aside to cool.
Assemble the roti: Divide the dough and mashed potato into 8 equal pieces.
The dough and roti are almost the same size.
On a lightly floured work surface, roll one of the pieces of dough into a circle, about 6 inches in diameter.
Remember to flour the work surface and rolling pin.
Place a portion of potato in the center and gather the edges of the dough and pinch to seal in the filling.
Don't be too skimpy on the potato!
Fill the remaining balls of dough with the filling. Turn over, so the sealed side is down and push down gently to flatten slightly.
Gently roll each one into a flat pancake, being careful not to push the potato out of the dough. You should not be able to see the potato through the dough.
Seal tightly with fingers.
Heat a cast iron frying pan to medium high. Brush the bottom lightly with canola or vegetable oil and place a roti in the pan. (A silicone pastry brush works well).
Brush the surface of the roti with more oil and cook until they puff up and the bottom is light brown in spots (see picture) - reduce heat to low if they are browning too quickly.
Brush lightly with oil.
Turn over when brown and delicious!
Sometimes they puff up like a balloon!
Keep the cooked roti warm on a plate covered with foil or clean towel. Enjoy!
Serve with your favorite curry.