Place pork, egg, salt, pepper and lemon zest in a food processor and process for 1 minute. Add cinnamon, nutmeg, pecorino and breadcrumbs and process for 30 seconds. Place in a bowl and stir through pistachios. Form pork mixture into walnut-sized balls.
Heat some olive oil in a large frying pan over medium heat. Brown meatballs, adding more oil as necessary. Add lemon juice, 250ml water and bay leaf and bring to a simmer. Add cannellini beans, squashing some of them with a spoon. Simmer 15 minutes or until meatballs are cooked and juices slightly thickened.