Combine the arugula, pistachios and garlic in the food processor and process until finely chopped.
Mix together the olive oil and lemon juice. Pour the liquids into the food processor while running, stopping to scrap down the sides as needed.
Add the salt and parmesan to the food processor and pulse a few times to combine. Taste test and add more lemon juice to combat bitterness, add more olive oil or water to make a thinner pesto.
To Store
Refrigerate for about 3 days in an air-tight container. Alternately, you can also freeze the pesto in ice cube trays and defrost in the microwave or by thawing in the fridge when ready to use.
To Use:
Spread on toast, use in a sandwich, or toss with pasta.
Recipe by Alison's Allspice at https://www.alisonsallspice.com/arugula-pistachio-pesto/