In a medium pot, bring water to a boil and cook the pasta al dente (it should have a bite to it, you don‘t need a lot of water, it must be well salted, don‘t add any olive oil to it). Reserve about 1/3 cup of pasta cooking water (it has a lot of starch and thickens the sauce nicely).
While the pasta cooks, prepare the vegetables: cut the zucchini in half longwise and then cut crosswise into ¼ inch / ½ cm slices, cut the bell pepper into ¼ inch / ½ cm strips. Pour boiling water over the tomatoes and pell them. Cut 2 tomatoes into cubes (about ¾ inch / 1.5 cm thick) and chop 1 tomato very finely. Chop the garlic very finely.
Heat the oil in a big pan over high heat, add the bell pepper and zucchini. Cook without stirring for 2 minutes (you have to give the vegetables time to brown), then cook, stirring, for another 2 minutes.
Add the garlic, French or Italian seasoning, chili flakes if using, and cook, stirring, for 1 minute.
Add the chopped tomatoes and pasta cooking water (if using canned tomatoes there's no need to add pasta cooking water). Cook for about 3 minutes or until thickened (some of the tomatoes should stay in pieces, and some should create a sauce).
Remove the pan from the heat, crumble the feta cheese over the sauce, and add cooked pasta. Season with salt and pepper (but carefully, the feta is already salty) and toss everything together.
Serve sprinkled with fresh herbs (optional).