Slit all the capsicums and remove seeds. (If banana chili, cut each into three pieces of about 2 inch length, slit them and remove seeds.)
Mix all the spices (except amchur) in besan. Heat a non sticking frying pan and pour 1 tspn oil. When the oil becomes hot, add the besan mixture. Stir frequently and roast till it turns brown (starts giving a typical flavour), about 15 minutes. Remove from heat and let it cool.
Mix coriander leaves, amchur and lemon juice to the besan mixture. Add about 200ml water to this mixture and make a thick paste (not very tight, loose than a chapatti dough). Fill this into all the capsicum pieces.
Heat the non sticking frying pan and pour 2 tspn oil. Put all the capsicum pieces (and leftover basen paste) into the frying pan and cook over low heat for 5-7 minutes. Reverse the side of capsicum pieces and cook for another 7 minutes. Remove from heat and cover with the lid.
Serve with roti, chapatti or use for making burger.