In a 3-quart saucepan, combine the oil, onion, and garlic. Cook over medium heat, stirring frequently, until the onion is tender, 8 to 10 minutes.

Drain the tomatoes and reserve the juice. If the juice is thick and there is no more than ½ cup in each can, then use in this sauce; if the juice is watery and plentiful, use it in another recipe, such as a soup or stew—the juice can be frozen.

Turn the tomatoes into a food mill and puree the tomatoes directly into the pan. Add the salt and hot red pepper flakes. Stir well. Increase the heat slightly and bring to a brisk simmer.

Adjusting the heat as the sauce cooks down, and stirring frequently, simmer briskly for about 12 minutes, adding the herbs in the last few minutes. The sauce should have thickened and reduced. If it needs to be thicker, continue to simmer briskly for a few more minutes. Taste and adjust the salt and pepper, if necessary.