Heat oil in a wide fry pan. Saute the onion while you wash, trim, and dice your tomatoes. Then add garlic to the pan.

Process tomatoes in a food processor. Add herbs and salt, and the onion mixture. Process some more until the sauce is relatively smooth.

Pour tomatoes back into the pan in which you cooked the onion. Bring to a boil, and boil, stirring often, to let liquid evaporate. This will probably be only a few minutes, until you get the consistency you want.

Serve, or use as a base in another recipe.