Since they are no longer common in physical stores, you can find them through these specialty retailers: Whatever Happened to Red Pistachios? - The Kitchn
Red pistachios, once a grocery store staple, are now primarily a specialty item found online. Originally, producers used red vegetable dye to mask shell stains and blemishes caused by traditional Middle Eastern harvesting methods. Today, modern California harvesting processes keep shells naturally clean, making the dye unnecessary. Where to Buy Red Pistachios
