In a small microwaveable bowl, place the water, soy milk and caster sugar. Mix well then place in the microwave for 10-30 seconds. The mixture should feel warm to the touch but not hot. Add the yeast to the milk mixture and mix well. Set aside for 10 minutes to allow the yeast on the surface to become frothy.

Meanwhile, in the bowl of a stand mixer, combine the psyllium husk powder, flours and the salt and mix well. Fit the dough hook and add the yeast mixture to the flours. Knead until you have a shaggy dough ball, around 2 minutes.
 

Add the vegan butter (which should be nice and soft) and knead the mixture on medium speed for around 5 minutes or until the dough looks smooth. Remove the dough and place in a lightly oiled medium sized bowl. Cover with a damp kitchen towel and leave to prove for one hour or until the dough has nearly doubled in size.

Once the first prove is over, very lightly dust a clean work surface with flour. Turn out the dough and gently push out any larger air bubbles with your fingertips. Using a rolling pin, roll out the dough into a sheet around 3cm thick. Use a circular cookie cutter around 8-10cm wide to cut out the donuts. Use a much smaller circle (I use the large end of a piping nozzle) to cut out the centre. You should get roughly 12 donuts.

Place each donut on a small square of parchment paper and carefully transfer to a deep baking tray. Cover with cling film or a damp kitchen towel. Don't discard the remaining dough: use the piping nozzle to cut out more donut holes. Cover the donut holes too and allow everything to prove for a further 40 minutes.

Once 40 minutes are up, add around 2-3 inches of vegetable oil to a deep, heavy-bottomed saucepan (I use a cast-iron dutch oven) and place over medium heat. Using a probe or candy thermometer bring the oil temperature to 180c. Alternatively, fill and heat a deep fat fryer to 180c.

Working one donut at a time, gently lift the donut from the baking tray (along with the baking parchment) and carefully slide it into the oil. The parchment will float off and can be removed with tongs immediately. Fry the donut for around a minute before flipping and frying the other side.

Remove from the oil with a spider or slotted spoon and lay on a baking tray lined with kitchen roll to absorb any excess oil then transfer to a wire cooling rack placed over a baking tray.

Allow the donuts to cool to room temperature. Meanwhile, prepare the glaze by whisking the icing sugar with the soy milk, liquid glucose (or corn syrup) and vanilla extract. Dunk the donuts one at a time in the glaze then set back on the wire rack to set. Once the glaze has fully hardened, the donuts are ready to serve.