Heat oil in a large frying pan over medium-high heat. Add cumin seeds and allow to splutter. Add onions. Sauté, stirring occasionally, for 2-3 minutes or until browned. Add ginger. Fry for a few minutes or until aromatic. Add turmeric powder, coriander powder, red chilli powder and asafoetida. Fry for a few minutes.
Stir in potatoes. Using a fork or potato masher, mash the potatoes lightly. Season with salt. Add coriander (cilantro) leaves. Stir. Heat throughly. Remove from heat. Allow to cool slightly.
For the batter:
Place chickpea flour (besan), rice flour, baking soda, asafoetida and red chilli powder in a large bowl. Season with salt. Add water little by little to make a smooth batter. Set aside.
Stuffed Raj Mirchi Poppers:
Cut open the chillies on one side. Remove seeds and membranes. Rinse under cold running water. Fill each chilli with potato masala. Set aside.
Meanwhile, heat oil for deep frying. When oil is hot enough, drop in the chillies one at a time. Fry until golden and crisp. (Do not overcrowd the pan. Fry in batches depending on the size of the pan). Drain on an absorbent towel. Serve hot with your favorite sauce or chutney.