In a large food processor, combine basil, 1 ½ cups arugula, lemon, olive oil, cashews and ½ tsp. of salt, garlic powder with 3 tbsp. of water and process until smooth (you may need to stop this once to scrape down the sides).
Add the remaining arugula and process until smooth. If you find that you need more liquid, add the additional tbsp. of water. Once you have the consistency you desire, taste for salt. Add up to an additional ½ tsp. of salt depending on your preference. Be sure to blend well.
Store in an airtight container for up to 1 week in the fridge.
Arugula: You can also use baby spinach or baby kale.
Cashews: You can use any nut or seed in place of cashews. You can use almonds, pine nuts, walnuts, pumpkin seeds, sunflower seeds would all be great here.
Garlic powder: I prefer garlic powder over fresh garlic in pesto so that the flavor is not overwhelmed by garlic. You can also use 1-2 cloves fresh garlic (grated or minced).
Fridge: Store in an airtight container in the fridge up to 1 week.
Freezer: Freeze pesto in ice cube trays in individual servings. Once frozen, transfer to a freezer safe bag for up to 3 months.