In a food processor, combine basil, cilantro, garlic, lemon juice, pistachios, and miso paste. Once fully combined, drizzle extra virgin olive oil through chute while the food processor is spinning, until it has become a smooth sauce. You may need to stop once or twice to scrape down the sides. Taste and add more salt, if needed. (Remember, both the miso paste and pistachios are salty.)
*Replace with more fresh basil leaves if you're not a fan of cilantro.