Cook the rinsed spinach in the microwave for about 60 to 90 seconds, or steam for about 2 minutes in a steamer basket over hot water. Drain well, squeezing all the liquid out with your hands.
Process the garlic, lemon zest, and red pepper in the food processor until the garlic is finely chopped. Add the spinach, arugula, pine nuts, and lemon juice, then process until you have a coarse puree.
Gradually add the olive oil, pouring in a slow stream while the machine runs. Stir in the Parmesan cheese and salt to taste. Serve as a topping for grilled hamburgers or vegan burgers.