Cook the tapioca with turmeric and salt in lots of water till done. I pressure cook for three whistles. Drain and reserve.
In a pressure cooker, combine all the ingredients for the masala and mix very well. Allow to rest for 15 minutes.
Pressure cook on high for 3 whistles or till the beef is done. Allow the pressure to go by itself.
Open the lid and check to see the moisture level. If there is too much liquid, cook on high flame till the liquid reduces to your likeness. Do not reduce too much, otherwise your biriyani will be dry!
In a large saucepan, heat coconut oil. Splutter mustard seeds. Add the shallots, dry chillies and curry leaves and fry till the shallots are browned.
Add the cooked tapioca and toss it. Now add the beef masala and give it a good mix.
Cook on simmer for 5-8 minutes for the flavors to incorporate.
Serve warm!