Sift dry ingredients into a bowl. Make the dough by adding yogurt little by little. Add water if needed. Knead the dough well to make it smooth and shiny. Rub oil, cover, let it rest- 30 minutes. Make thin chappatis. Transfer chappathi to a skillet, over medium heat. When you see small bubbles, turn over, cook about 30 seconds. Increase the heat, press chappathi with a cloth, chappathi will puff- about 30 seconds, Turn over, press chappathi to puff up. Remove from the skillet.