1) Pressure cook sweet potato with skin on for 2 whistles. Ensure you have scrubbed the skin well. 2) Once the pressure releases, mash it well with pav bhaji masher (do not peel as the skin contains a lot of vitamins too). Add the masala powders, coriander, curry leaves, green chillies, turmeric and all other ingredients except oil and mix well with your hands. Do not add water at all as the tuber itself is starchy. 3) Divide the mix into equal parts and make elongated croquettes. Place in a slightly large oiled bowl, cling wrap and refrigerate for 10 - 15 minutes . This adds firmness to the croquettes. If making for a party / potluck, refrigerate for upto 2 hours under cling wrap. 4) Meanwhile, dry roast sooji / semolina if using for outer cover. If using bread crumbs, make sure they are fresh. Else, make a batch quickly with toasted bread. 5) Take out the refrigerated croquettes. Drip them lightly in the cornflour slurry and quickly roll them in the roasted rava or bread crumbs. Repeat till all the mixture is exhausted. 6) Shallow fry them in batches and drain on tissue paper. 7) Serve hot with steaming cups of tea and /or along with green chutney and ketchup (for kids events)