First, spiralize the zucchini. (I like to use the thicker of the two blades so the “zoodles” have more bite and don’t become mushy.) Then place the zucchini noodles in a colander, sprinkle with 1/2 teaspoon salt, toss well, and allow to sit for at least 15 minutes or up to an hour or so. When ready to add to the sauce, use a clean tea towel or two sturdy, lint-free paper towels and squeeze the excess moisture out of the zucchini. Zucchini has a very high water content and this will create a better texture noodle and prevent the sauce from becoming watered down. At this point, you may wish to snip the long strands into shorter pieces for easier eating later.
For the sauce: In a large skillet (a 10-inch diameter works well), heat the olive oil over medium heat. Add the garlic and sauté 1 minute or until fragrant but not turning brown. Add the anchovies, mashing them with the back of a spoon. (They will dissolve into a paste and flavor the sauce with no obvious pieces.)
Add the tomatoes, capers, salt, pepper, and sugar. As the tomatoes cook and soften, mash them with a fork to help form a chunky, rustic sauce. Simmer the mixture for 5 minutes or until the tomatoes break down.
Add the squeezed zucchini, and cook for 2 to 3 minutes or until hot. Sprinkle with feta and torn basil, if using. Enjoy as is or with a piece of crusty bread to mop up the sauce.