Roughly chop the Pistachios (0.5 ounce).
Slice off the stems of the Brussels Sprouts (6 ounce). Begin pulling away the brussels sprout leaves and place them in a bowl. You will only need the brussels sprout leaves, so discard the cores and any damaged outer leaves.
In a saute pan over medium heat, add the Olive Oil (1 fluid ounce), brussels sprouts, chopped pistachios, Kosher Salt (1/4 teaspoon) and Ground Black Pepper (1 pinch). Saute until leaves begin to soften but are still bright green, about 2 minutes.
Add the Unsalted Butter (1 1/2 tablespoon) and melt to coat the brussels sprouts. Squeeze the Lemon (1/2) and toss the lemon juice with the brussels sprouts.
Transfer to a plate or bowl and serve.