Lightly boil cauliflower (including leaves and stem).
Transfer cauliflower into a blender with 1 cup of the water it was cooked in. Add more water if necessary.
Add the tahini, lemon juice, nutritional yeast, salt, olive oil, turmeric and mustard.
Blend and season to taste.
If additional ‘zing’ is required, add more lemon. You may also want to add more tahini, yeast or mustard.
Gently heat sauce in a pan prior to serving.