Add salt and cumin seed to the flour. Blend vanaspathi to the flour evenly. Gradually add milk and knead to a stiff dough. Pat and knead several times. Make balls and roll into thin chapatis. Place chapati on a hot tawa and prick with a knife all over on top. Keep pressing the chappati using a clean cloth, by gently turning it and giving pressure all over. Turn over to direct flame and puff up. Apply little oil to one side after removing from fire. These chapatis can be kept for a week.