Wash chilies and remove stalk. Make a slit lengthwise keeping it joined at other side. Likewise cut all chilies.
Preheat 2 tbsp oil in a wok. When oil is hot add asafoetida, cumin seeds. After sauteing cumin seeds for while, add turmeric powder and gram flour. Saute on low flame until gram flour turns light brown in color. Now add coriander powder, fennel powder and saute for few more minutes. Turn off the flame now. Add mango powder, garam masala and salt in the masala. Masala for stuffing the chilies is ready.
Stuff the slit chilies with this masala. Take one chilly in your, open from slit side and stuff it with masala with help of spoon. Press it gently and likewise stuff all chilies.
Add rest of the oil in a wok and allow it to heat. Place the stuffed chilies in pan and cover. Cook for 2 to 3 minutes on low flame. Open the lid and flip the side of chilies. Chilies kept in the center are roasted well. With help of tongs, flip the sides and take them out in a plate. Bring rest of the chilies in center. Keep tossing and flipping sides and take them out in a plate. Besan stuffed green chilly is ready. Serve these piping hot and spicy masala chilies with your meals and relish eating.