Blend the Ingredients: In a food processor, combine arugula, Parmesan, toasted nuts, garlic, and lemon juice. Pulse a few times until roughly chopped.

Incorporate the Oil: With the processor running, slowly drizzle in the olive oil until the pesto reaches a smooth consistency.

Season to Taste: Add salt and freshly ground black pepper as needed, pulsing once more to combine.

Store & Serve: Use immediately or store in an airtight container with a thin layer of olive oil on top to preserve freshness. Refrigerate for up to a week or freeze for longer storage.