Put all ingredients (except the pepper) into a high speed blender and blend on high until smooth and creamy.
Add more water or salt to get the flavor and consistency you want.
Add pepper if using and pulse to incorporate.
Notes
This makes a little under 2 cups of cashew cream. Serving size is ¼ cup.
If you are not using a high speed blender, there are a couple of options for making your sauce smooth: You can use a coffee grinder to grind the nuts into a fine powder (do not soak for this option), or soak them overnight (or for at least 2 to 3 hours). If you forget, you can also boil them for 30 minutes.
Add the pepper depending on the recipe you are using this for.
Be aware that your cream may have a slight purple tint if using walnuts. This is due to the walnut skin that could be on your walnuts. It's totally normal and can come out when walnuts get wet and heated which happens while blending the cream.