Pistachio Butter Filling

• 1 bunch (about 1½ cups) of cilantro leaves
• ½ jalapeño pepper, seeds removed

Wash and dry the cilantro. By hand or in a food processor, chop the leaves with the jalapeño and the pistachios until fine; then add the butter, lime zest, and juice. Work the mixture until you have a smooth paste. Season it with salt to taste.