Wash and pat dry the chillies, subsequently slit them in middle.
In a pan, heat one tablespoon oil. Add the chilli powder, garam masala powder, chaat masala, turmeric powder, 1/2 teaspoon salt and grated boiled potatoes to it. Mix well and switch off the heat. Divide this into 12 equal portions.
Stuff this mixture into the slitted Red chillies.
In a mixing bowl, add the gram flour, remaining 1/2 teaspoon salt and about 1/2 cup of water. Add 1 tablespoon of oil and mix well to make a smooth batter and keep it aside for 10 minutes.
Heat sufficient oil in a Pan/Kadhai. Dip the stuffed chillies in the gram flour batter, coat them nicely and deep-fry until golden brown.
Keep in mind which kind of chilli you want. You are ideally looking for chilli which can be stuffed, hence big meaty chilli is ideal choice.
Check how spicy you wish your chilli to be, I have gone for mild ones.
You can remove seeds from chillies after slitting chilli.
Be extra vigilant while frying as sometimes chillies might splutter.