First cook the spaghetti (check the package for specific instructions) by bringing a large saucepan of water to a boil, adding a couple of large pinches of sea salt and then the spaghetti; it should take about 8-10 minutes to cook. Stir every so often so the strands of pasta don't stick together. When the pasta is just cooked (al dente), drain it in a colander, drizzle with a little olive oil and then mix to lightly coat the pasta and prevent the strands from sticking together. Set it aside.
You can use the same saucepan to make the sauce. Pour in the 3 tablespoons of olive oil and heat over medium heat, then add the zucchini and sauté for 4-5 minutes, before adding the garlic and herbs and mixing well. Sauté for a couple more minutes, to allow all the flavors to come together and the zucchini to cook through.
Return the cooked spaghetti to the pan and heat through, then mix in the cheese and lemon zest, and season with a little sea salt (you may not need much since the feta cheese is salty) and a good grind of black pepper. Serve, with a little more grated cheese sprinkled over, if you wish.
Reprinted with permission from Sterling Publishing. Although the book says this recipe serves 2, we got 4 servings out of it.