Using your fingers, remove the tomatoes from the can one by one and crush them, letting the juice and seeds run back into the can. Put the tomatoes in a bowl and strain the juice over them.

In a 2-quart saucepan, lightly brown the shallots and garlic in the olive oil. Make an herb sachet by tying together the basil, tarragon and thyme in a double layer of cheesecloth. Add the tomatoes and the sachet, bring to a boil, and reduce the mixture over medium heat until it is dry. Put the mixture through the fine blade of a food grinder or through a food mill. Season with salt and freshly ground pepper.