Tip the flour into a bowl with 1/4 tsp salt and the turmeric, if using. Whisk in 300ml cold water, breaking up any lumps.

Bring 300ml water to the boil in a medium pan over a medium heat, then pour in the batter, stirring for a few minutes until thickened. Cook for 5 mins more, stirring to prevent it from sticking to the pan. Pour into an airtight container or small loaf tin (you may need to oil the container if you’re worried about it sticking). Smooth the surface, then leave to cool for 30 mins. Chill until set, about 2 hrs or overnight – it should be firm enough to slice or cut into cubes. Will keep chilled for up to three days.