Soak the dried mushrooms in boiling water for 20 minutes - don't throw the soaking water away!
Fry the diced onion in the olive oil for 10 minutes or until soft and translucent
Add the chopped garlic and fry gently for a further minute
Add the white wine and cook gently until the liquid is reduced by half, remove from the heat
Transfer to a blender. Add the drained mushrooms, butter beans, herbs, spices, tamari, miso and 125ml/half a cup of the mushroom soaking water (keep the rest to use as stock for something else, it's delicious!)
Blend until well combined - it doesn't need to be smooth as smooth
Transfer the blended mixture to a large bowl and start by adding 125g/one cup the vital wheat gluten flour. Mix well. Add enough flour to make a soft dough which you can roll into sausages between your hands. It should be a little bit sticky but not leave dough all over your hands. Add a bit more flour if it is too sticky.
Divide the dough into 16 equal pieces. Roll each piece into a sausage shape about 10cm/4 inches long (or, the width of your bread roll!)
Wrap each sausage tightly in cling film (I hold each end of the cling film and spin it, dramatically, all chef like!) then in foil and steam them for one hour.
Leave to cool (they firm up a bit as they cool) then fry two vegan bratwurst per person in a little olive oil until browned and cooked through.
To serve, place a spoonful of caramelised onions into each bread roll, top with two bratwurst and a squirt of mustard, wash it down with some hot Glühwein. Alternatively serve them up with some sauerkraut and potato salad with a big glass of beer!