Open the can of tomatoes and pour off the juice into a bowl. Use the lid to press against the tomatoes to extract as much juice as possible. Squeeze the tomatoes to a pulp using your hands. Reserve the juice and pulp separately and set the empty can aside.
Heat the oil in a heavy saucepan over medium-high heat until hot. If using the jalapeno, tilt the pan to collect the oil in a little pool against the side and drop the jalapeno into the oil. Cook until light brown, about 2 minutes. Remove the jalapeno and reserve.
Add the onion to the pan and cook, stirring occasionally, until soft, about 2 minutes. Add the garlic and cook briefly until light gold. Add the bay leaf. Add the tomato juice and bring to a boil. Simmer rapidly for several minutes. Add the crushed tomato pulp. Then rinse the remaining pulp out of the can by filling it halfway with water and add that to the pan. Add the jalapeno, and salt and pepper, to taste, and return to a boil. Add the dried tomatoes and stir. Lower the heat to medium and simmer, stirring occasionally to prevent scorching, until the mixture thickens and the tomatoes have turned an orange-red versus the pale blue-red they were straight from the can, about 30 minutes. Add the oregano halfway through the cooking.
Discard the bay leaf. Peel, seed, and mash the jalapeno with a spoonful of the sauce and pass at the table so diners can add as much heat as they like to their plates.
Variation for quick tomato sauce: Substitute 2 pounds vine-ripened tomatoes for the canned tomatoes. Peel the tomatoes, cut in half crosswise, and squeeze out the juice and seeds over a sieve suspended over a bowl to collect the juice. Chop the tomatoes. Proceed as directed, omitting the dried tomatoes and using jalapeno, if desired. You should have about 2 1/4 cups sauce. The recipe may be increased proportionately.