Pistachio pesto (pesto di pistacchi)

Every year, my aunt holidays in Lampedusa, an islet just south of Sicily. And every year, she brings back local delicacies, such as fennel liqueur and fresh capers. My favourite gift is always pistachios. The green and purple gems sparkle in your hands, and the real fresh Bronte pistachios have an aroma far superior to anything you can find on a shelf. I figured the best way to take advantage of this precious gift was to make pesto. I use it on top of pasta (thin with a few tablespoons of the pasta cooking water and, if needed, more olive oil), but it can be spread over bruschetta, pizza and sandwiches, drizzled over salads and used on pretty much everything you can think of. For a variation, add a tablespoon of ricotta. Or change the herbs: try sage, parsley or mint, or a mix of everything.