To make the pesto: In a food processor, combine the arugula/basil, cooled almonds, Parmesan, garlic and salt. Pulse while drizzling in the olive oil. Stir in the lemon juice and season to taste with freshly ground black pepper.
Toast the almonds: In a large skillet over medium heat, toast the almonds, while stirring frequently, until the almonds are fragrant and turning lightly golden at the edges. Transfer the almonds to a bowl to cool.
Preheat the oven to 500 degrees Fahrenheit with a rack in the upper third of the oven. Or, if you're using a pizza stone, make sure it's in the oven on the appropriate rack (consult manufacturer's directions).