Wash and dry the papdi. String each bean and break it into 2 or 3 even sized pieces, where necessary removing remnants of strings.
Heat the oil in a non-stick pan and fry the sliced onions till pink in color.
Add 1 tsp garlic ginger paste and fry for 1-2 minutes.
Add the walor papdi, potatoes, turmeric powder, coriander-cumin seeds powder, chili powder, sugar, salt (as per taste), along with 1 cup of water and mix well.
Cover and cook on a low flame for 20 minutes or till the walor papdi and potato is cooked, while stirring occasionally. Serve hot with rotis.