Fill a large pot with salty water and bring it to a boil over high heat. Add the pasta to the pot while you cook the zucchini.

Cook until al dente according to the package directions. Reserve about ½ cup of cooking water when you drain the pasta.

Cut the tomatoes in half, and dice the onion and zucchini. If the zucchini is large, cut it lengthwise. Then, cut each half into three long batons. Slice off the seeds from each baton and cut them into ½-inch cubes.

Heat the olive oil over medium heat in a large non-stick sauté pan. Add the red onions and cook, stirring frequently, until very soft and pale purple in color, about 5-6 minutes. Do not brown.

Add the zucchini, chili flakes, about ¼ teaspoon of salt, and freshly ground black pepper. Give it a good stir and cook over medium-high heat for about 10 minutes, or until the zucchini are cooked but still crisp, not mushy.

Add the tomatoes, stir, and cook until the skins burst and the tomatoes begin to release their juices, for about 4 minutes. Taste and adjust the seasoning according to your taste.

Add the pasta and parsley to the pan and toss gently to combine. If the pasta dries out, add a touch of pasta cooking water (you don't need all of it, but use just as much as you need to keep everything moist and juicy).

Taste again, and make sure you're happy with the seasoning.

Remove from the stove and serve immediately with a drizzle of extra virgin olive oil and black pepper, garnished with fresh parsley and parmesan cheese, if desired. Enjoy!