One key to making a great-tasting pasta dish with an uncooked tomato sauce has nothing to do with adding extra-virgin olive oil, butter or cheese. My secret is to use the liquid that almost all tomato sauces give off as they sit. I undercook the pasta slightly, drain it, return the pot to the stove and spoon in the liquid. I add the pasta and stir over moderately high heat until it’s just tender and nicely coated. Not only is the pasta perfectly cooked, it’s infused with flavor.