In a large bowl, stir together flour and salt. Make a well in the center and add some of the water to the well. Using your hands, mix, adding water as necessary, until a tacky dough is formed.
Turn dough out onto a lightly floured work surface and knead until smooth and elastic, about 8 minutes. Transfer to a large, clean bowl and cover with plastic wrap; let stand at room temperature 10 to 15 minutes.
Divide dough into 8 equal pieces. Roll each piece into a ball and cover with a clean kitchen towel. Working with one ball of dough at a time, roll ball in flour; shake off excess. Place dough on a lightly floured work surface and flatten with the palm of your hand. Using a lightly floured rolling pin, roll out dough to a 1/4-inch-thick round. Brush half of the round with oil and fold in half to form a half moon shape. Brush half moon shape with oil and fold in half again. Gently roll dough to flatten slightly. Form dough into a ball and roll out again to a 1/6-inch-thick round (about 6 to 7 inches in diameter). Repeat process with remaining balls of dough, keeping rounds covered with a kitchen towel as you roll.
Heat large, dry cast-iron griddle over medium heat until hot. Working with one round of dough at a time, place on griddle and cook until bottom is golden and browned in spots, about 30 seconds. Brush opposite side with oil and turn; cook until deep golden brown in spots, about 30 seconds to 1 minute. Turn again and cook, gently pressing with tongs, until chapati is cooked through and puffy, 30 seconds to 1 minute more. Remove chapati from skillet and keep warm while cooking remaining chapati.