Prepare the Pistachio Mixture: In a food processor, combine the olive oil and pistachio nuts. Pulse for about 1 minute or until the mixture is well combined, scraping down the sides of the bowl as needed.
Add Feta and Herbs: Once the pistachio mixture is combined, add the feta cheese, coriander leaves, chopped dill, and garlic powder to the food processor. Pulse for another minute until everything is well incorporated.
Add Yogurt and Lemon: Scrape down the sides of the bowl and add the Greek yogurt, lemon juice, and zest (if using). Pulse briefly to combine.
Adjust Seasoning: Taste the dip and adjust the seasoning as needed, adding salt to taste.
Serve or Store: Transfer the dip to a serving bowl and serve immediately, or store it in an airtight container in the refrigerator for up to one week.