Wash and wipe bhindi with a wet cloth. Cut both the ends and make two inch long pieces. Slit bhindi horizontally without cutting them into two. Peel, wash and slice the onions. Remove stems, wash green chillies and slit them into two. Heat oil in a kadai and add cumin seeds. When they change colour, add onions and saute till light golden. Add green chillies and saute for half a minute. Add bhindi and sprinkle the red chilli, coriander and turmeric powders. Mix well. Cook covered over low heat stirring occasionally. Add salt and amchur. When bhindi is almost cooked, finish cooking by cooking it on high heat for two minutes