In a blender or food processor, whizz all the ingredients except the vital wheat gluten, until smooth.
Pour the mixture into a large bowl. Add the vital wheat gluten and stir with a wooden spoon until it forms a wet dough.
Knead for about 7 minutes. It is ready once the dough appears drier, has defined strands, and bounces back when stretched.
Set a steamer basket over a pan of simmering water.
Divide the dough in half and shape into logs. Roll each log tightly, first in non-stick baking paper, followed by foil. Twist the ends to seal it tight, like a sweet wrapper.
Steam the seitan for 30 minutes, then remove from the steamer and leave to cool for 30 minutes (I find it firms up as it cools). Tear into chunks and add to any dish that traditionally uses chicken (like ‘Butter Chicken’). Alternatively, cool completely and store in an airtight container in the fridge for up to five days.