Combine whole wheat flour, salt, asafoetida, turmeric powder, coriander powder, paprika and mixed herbs in a large bowl. Mix well, add sweet potato and three tablespoons oil, mix well and knead into a soft dough.
Cover and set aside for two to three hours. Divide the dough into marble sized portions and shape into balls. Roll them into small puris. Heat sufficient oil in a kadai.
Deep fry puris, a couple at a time, on medium heat till lightly browned from both the sides. Drain on absorbent paper. Serve hot.