While you can use freshly made idlis for this recipe, using leftover idlis is recommended for the best results. Freshly made idlis might be too soft and delicate, making them prone to breaking or becoming mushy during frying. Leftover idlis that have been refrigerated overnight firm up slightly, which makes them easier to handle and ensures a better texture when fried. If using freshly made idlis, refrigerate them for a few hours before cutting and frying.