Wash, cut into half and pressure cook potatoes for 3 whistles or cook in open pan until soft. Meanwhile peel, wash and grate beetroot, finely chop onion, green chilies, coriander leaves. Once pressure released peel and mash potatoes.
In a large bowl take grated beetroot, mashed potato, onion, green chilies, coriander leaves, red chili powder, turmeric powder, cumin powder, amchur powder, black salt and table salt mix well to combine. Add bread crumbs and mix well.
Divide dough into equal portions (comes around 9 to 10 pieces) and roll between both hands to form in log shape, slightly press to flatten. You can also shape in normal round cutlet shape or use cookie cutter to cut in heart shape, whatever that you like. Repeat same for rest (you can keep cutlets covered in refrigerator for 30 mins to an hour to firm them).
In a small plate or bowl mix maida or corn flour with 2 to 3 tbsp of water without any lumps and not very thick, in another small plate take bread crumbs. Dip cutlet in maida mix to coat all sides then coat with bread crumbs well, repeat same for rest.
Heat a pan or tawa add 1 tbsp oil, place 4-5 pieces of cutlet and cook in slow to medium heat until it becomes light brown, turn to other side and cook again until light brown, if needed drizzle some oil, repeat same for rest of pieces.
Serve hot or warm with green chutney or sauce.
You can avoid onion if wishes. You can avoid coating in maida mix, bread crumbs and directly cook cutlet, this way it takes very less oil too. If you are not able to bind dough, add more bread crumbs. You can also deep fry the cutlets if preferred or making in large batch. You can stuff the cutlets with peanuts, raisins etc You can make the cutlet and freeze it in a box or zip lock bag and cook it later.