Combine flours, salt, psyllium husk powder, oil and sour cream in a large bowl. Stir, then add 250ml (1 cup) of boiling water. Stir again to combine, then add the remaining 125ml (1/2 cup) boiling water if you need it. I always add the full amount, but you might need less. If in doubt, err on the side of caution – you can always add more water later.
