For an extra smooth sauce, use a high-powered blender and soak the cashews for a longer period, even up to 30 minutes. Adjust the amount of nutritional yeast to taste. More yeast will result in a stronger 'cheesy' flavor. Experiment with different mustards! A spicy brown mustard or even a touch of Dijon can add a unique twist. This sauce can be stored in the refrigerator for up to 3 days. Reheat gently over low heat, whisking frequently, and adding a splash of water if needed.