This nut butter should be green, lightly sweet, and very delicious. You can add more or less honey to suit your taste (start with 1/4 cup and adjust), and more or less salt. Adapted from a recipe at Serious Eats. http://bit.ly/gbTmFo
Preheat oven to 375°F Spread pistachios and almonds on a baking sheet. Toast until lightly fragrant, 7-8 minutes.
Quickly transfer to the work bowl of a food processor, fitted with the steel blade, to avoid over-cooking. Process until a smooth paste forms, 8-10 minutes. Stop the processor and scrape down the sides of the bowl with a spatula once or twice.
Add salt and honey and process until combined. With processor running, drizzle in oil until very smooth, another 7-8 minutes. Transfer to jars or airtight containers and refrigerate for up to 2 months.