In a large heavy pot, gently heat olive oil, onions, sea salt and a little freshly ground pepper (and the chili pepper, if using) and saute over low heat until the onions are soft, about 10 minutes. Add carrots and saute another 5 minutes. Add the San Marzano tomatoes and their liquid and break up the tomatoes with a wooden spoon (or just crush them with your hands, like I do). Add the herbs and sugar, if you are using it. Simmer gently, uncovered, for about 20 to 30 minutes, until the sauce thickened Has.