Pulse spinach, basil, walnuts, garlic and lemon juice in a food processor 5-10 times or until the ingredients breakdown. Stream in 1/2 cup of olive oil from the top while you continue to pulse.
Stop the food processor and scrape down the sides. If the pesto is too thick, use the remaining 2 tablespoon of olive oil. Season the pesto with 1/4 teaspoon of salt, and adjust to taste.
TORTELLINI SALAD
Heat a large pot of water on the stove and cook the cheese tortellini to package directions.
Toss the pasta with half of the pesto mixture, tomatoes, mozzarella, and a handful of parmesan cheese. Adjust with additional pesto to taste. Season with salt and pepper.