Add the roasted salted pistachios and milk to a high-speed blender and blend on high speed for 1 to 2 minutes until the mixture turns pale green and completely smooth.

Pour the blended mixture through a fine mesh strainer into a clean bowl, pressing gently with the back of a spoon to extract all the liquid and remove any solids.

Stir the honey or agave syrup and vanilla extract into the strained pistachio milk until fully dissolved and evenly distributed.

Add a pinch of sea salt to the pistachio milk, stir thoroughly, and taste, adding another tiny pinch if the flavor feels muted.

Place the pistachio milk in the freezer for 2 to 3 minutes, ensuring it is very cold but not frozen before frothing.

Pour the cold brew coffee or iced espresso into serving cups, filling each about three-quarters full and leaving room for foam.

Use an electric milk frother (or electric whisk) to froth the chilled pistachio milk for about 1 minute, holding the frother just below the surface until the mixture doubles in volume and becomes airy.

Hold back the foam while pouring any remaining liquid into the coffee, then spoon about 2 to 3 tablespoons of pistachio foam on top of each cup.