Add the nuts in the mason jar and fill the jar with water. All of the nuts should be covered. Allow this to soak overnight.
Drain the water from the nuts and add the soaked nuts to a blender. Add the remaining 4 cups of water to the blender with vanilla and sea salt. Blend until the nuts are all broken down and the mixture is frothy.
Place the nut milk bag or kitchen towel over a large bowl and pour the milk into the bag or strainer. Squeeze the liquid through the bag or strainer until all of the liquid is extracted. Pour the milk back into the Mason Jar and store for a week or so in the fridge!