Prepare the dough for the ribbons (Steps 1 and 2) 2 to 3 days in advance and refrigerate it, covered. Bring it to room temperature and proceed with Step 3.
Combine the roti flour, salt, coriander, cumin, and turmeric in a medium-size bowl. Drizzle the oil over the flour mixture, and rub the flour through your hands to evenly distribute the oil.
Add the yogurt, a tablespoon or two at a time, stirring until the flour comes together to form a soft ball. Using your hand (as long as it’s clean, I thi