Place the flour in a bowl and make a well in the center. Add the sourdough discard and salt and mix it until the sourdough discard is evenly dispersed.
Trickle water in slowly and knead into a pliable but fairly stiff dough. A dough that is too soft will make it harder for you to roll out and transfer the rotis to the griddle. Cover the dough with a damp cloth, or place it in an air-tight container, and let it stand for at least half an hour. For longer storage keep it in the refrigerator.
Divide the dough into 16 pieces. Roll each into a smooth ball. Dust the rolling surface with flour and roll out each ball of dough into a circle about six inches in diameter. Try and roll evenly, and don't make the rotis too thin. This will help your rotis puff up.
To make ghadhichi poli, or a folded roti, roll the ball of dough into a disc about four inches. Brush on a tiny bit of oil on the disc, just a couple of drops, fold it over once, run the brush or your fingers with oil over the surface once more, then fold again into a triangle. Dust the triangle with more flour and roll, as best as you can, into an even, six-inch circle.
Heat a tava (an Indian griddle) or a cast iron griddle over medium high heat. When the griddle is hot, place a roti on the griddle. Wait a few seconds until you see bubbles appear. Then, using a wadded-up flour sack cloth or even a paper towel, press down gently on the roti, moving it a bit as you do so, to ensure it cooks evenly. You can use a spatula to do this, but be careful as you don't want to tear the roti.
Use a spatula to flip the roti. At this stage you can apply a bit of oil to the roti or spritz on some cooking spray if you wish. Press on the edges of the roti (gently) with the spatula or wadded up towel, which will help the roti puff up.
When golden-brown spots appear on the underside of the roti, flip it over once more and let the top finish cooking. You are done when there are golden-brown spots on both sides of the roti.
Wrap the rotis as they come off the griddle in a kitchen towel. Serve hot.