Sift flour, baking powder, and salt in a large bowl. Add oil and enough water until a dough forms, not too dry. Allow the dough to rest for 30 minutes, cut dough into 8 equal pieces, and form balls. Allow dough to rest for 2 minutes. Roll dough out on floured board until it measures 6 to 8-inch disks.
Heat a griddle over medium heat, when hot brush the griddle with oil. Brush the roti disks with oil on both sides, place on cast-iron hot griddle, and cook until top starts to blister. Flip roti and cook for 1 minute more. Serve warm.