Add the cashews to a bowl and pour boiling water on top. Stir and then let the cashews soak for 30 minutes-1 hour until softened.
Strain the soaked cashews and add them to a blender with the water, nutritional yeast, tapioca flour, apple cider vinegar, and flour.
Blend together until the mixture is completely smooth. It will be runny and thin at this point but thicken up once heated.
Pour the blended cheese mixture into a non-stick saucepan or saute pan. Then, cook the mixture over low heat, stirring constantly, until it has thickened. The cheese will start to clump up and look curdled, but keep stirring and cooking it until it has thickened (about 5 minutes). When it's done it will be stretchy, yet firm, and smooth.
Remove the cheese from the heat and serve immediately or add to your favorite dish. The cheese will brown on top when broiled but still stay melty and gooey inside. Enjoy!