Boil the potatoes in a pressure cooker till they are perfectly cooked.
Peel the potatoes and mash them well.
Slightly dry roast the fennel and coriander seeds and then crush them coarsely with a mortar and pestle.
In a big bowl add the mashed potatoes ,crushed fennel and coriander, mint powder,chopped green chili and fresh coriander, mango powder, salt ,chili powder and mix well.taste the potato mix now and adjust if any thing needed.
Batter- take a bowl , add the sieved gram flour, salt, chili powder, turmeric, chili powder, asafoetida and water and mix well.
Make a smooth medium thick batter of coating consistency.add soda(just before frying ) and mix.
Wash, wipe and slit the green chilies from the center.
Remove the seeds if you want.(This step is optional if your chilies are hot )
Now stuff the chilies with the potato mixture and keep aside.
Frying the vadas.
Heat enough oil in a deep wide pan.
Dip the stuffed chilies in the gram flour batter and coat well from all the sides and then gently drop few at a time in the medium hot oil.
Let them cook for few seconds then flip the side gently.
Cook till they become golden and crisp from all the sides.
Now remove from the pan and drain on a paper towel to remove the excess oil.
Serve hot mirchi vadas with ketchup or any tangy chutney of your choice.