Steam damp spinach in a large
covered pot over medium heat
until tender and wilted, about
5 minutes. Drain. Squeeze out
excess water. Transfer to a food
processor. Add garlic, pepper
flakes, nuts, and Parmesan to
bowl. Pulse until finely ground.
With machine running, add oil.
Stir in lemon zest. Season with
salt. Serve with toasted bread
drizzled with oil and topped with
sardines and currants. Squeeze
with lemon before serving.
Skinless boneless sardines in olive oil are best for this dish.