If you do not have a high-speed blender or you want to maximize nutrition, soak the pistachios in water for at least 4 hours, or overnight in the refrigerator. Drain the pistachios and rinse until the water runs clear.
Add the pistachios and two cups of the water to a blender. Start on a low setting and quickly increase the speed all the way to the highest setting until the pistachios are totally pulverized. This could take 2 minutes in a high-powered blender or longer in a regular blender.
Add 2 cups more water*, your sweetener of choice (if desired), and vanilla extract. Blend on high until well blended.
Strain the milk through a fine mesh strainer or cheesecloth. Store the milk in a covered container in the refrigerator for up to 4 days. Stir well before serving, and enjoy it chilled.
