Use a julienne peeler or mandoline to slice the zucchini into noodles. Set aside.

Combine the basil and garlic in a food processor and pulse until coarsely chopped. Slowly add the olive oil in a constant stream while the food processor is on. Stop the machine and scrape down the sides with a rubber spatula. Add the lemon juice and Parmesan cheese. Pulse until blended. Season with salt and pepper.

Combine the zucchini noodles and pesto. Toss until well coated. Top with tomatoes if using. Serve at room temperature or chilled.

If you want to cook the zucchini noodles, add them to a skillet and sauté over medium heat for a few minutes.