Hi Jayne, yes tapioca flour and starch are the same. You could use any binding agent like chickpea flour, or even rice flour. It really doesn’t matter since the quantity of flour is very little. Instead of whole cashews, you can perhaps use cashew nut milk, for a smoother consistency. I am a little averse to commercial nut milks because of all the additives and preservatives they contain. So, if you are buying cashew milk, read the labels. You can also soak the cashews overnight and grind them to a smooth paste first before adding the mushrooms and broth. Thanks so much for the feedback!!