Add a can of coconut milk, water, nutritional yeast, tapioca starch, salt, lemon juice, mustard, paprika, garlic powder, and turmeric, then give it a stir with a whisk until all of the starch is dissolved. (Don't turn on the heat until the starch is fully dissolved.)
Turn the stove to medium heat and stir frequently until your cheese sauce thickens and starts to boil. Then turn down the heat to low and stir constantly for about 30 more seconds before taking off the heat.
Notes
Use full-fat coconut milk for the creamiest cheese sauce, but you can use light coconut milk for a lower-fat option.
Add the tapioca starch to cold coconut milk. If you try to add this after you start heating the sauce, it will clump and not dissolve.
Tapioca starch will give you the best results for a cheesy texture that won't become gloppy when it starts to cool down.