Cook tapioca with salt till it becomes soft. Mash tapioca & keep it aside.
Marinate the cleaned beef with onion, ginger garlic, masala powders, vinegar & salt. Cook the marinated beef till it becomes tender. Add the mashed tapioca to beef & mix well.
Meanwhile fry scraped coconut with chilli powder & coriander powder till it becomes golden brown (keep aside 2 tsp of coconut for garnishing). Grind it. Add ground coconut mix to beef & tapioca & mix well.
Heat oil in a pan & splutter mustard seeds. Add small onion & saute for 3-4 minutes. Add beef tapioca mix & stir for 4-5 minutes. Garnish with curry leaves & fried coconut.