Wash and slit the chillies and remove the veins and seeds inside.
Bring water to a boil with some salt and add the green chillies and blanch for a minute and drain. If you are not sure of how spicy the chilli pepper is, then blanching is a good way to reduce some heat without losing the flavour. This step also helps the peppers to absorb less oil while shallow frying.
Boil the potatoes, peel skin, mash coarsely and keep aside.
Dry roast saunf in a pan and pound it in a mortar pestle to get a coarse powder.
In the same pan, dry roast besan/gram flour until the raw smell goes away and gives its aroma and cool it completely.
Heat a tsp of oil in the same pan and add onions, sauté for a minute to soften. Remove and keep aside. This step is optional but lends extra flavour to the dish.
In a bowl, mix the onions, mashed potato, roasted besan, salt, spices, chopped coriander, lemon juice and mix thoroughly.
Fill the chillies with this mixture tightly; it really takes lot of stuffing inside. Wet your hands and press on top of the stuffed mixture, you can even sprinkle few drops of oil on the top of the stuffing in the pepper. This helps in holding the mixture tight without spilling it when frying/roasting it.
Heat the oil in a tawa and crackle jeera and ajwain and add a pinch of hing. Place these stuffed chillies with the stuffing facing down (always shallow fry the stuffed side first). Let it roast on low flame until it is fried, it takes 6-8 mins approximately, close it with lid while roasting. Now turn and roast on the other side for 3-4 mins.
Garnish with a dash of yoghurt and coriander leaves.