But when tomatoes are in season, just look for whatever's best. Choose tomatoes that feel heavy for their size, and, ideally, smell like a tomato, feel slightly sticky, and have part of the stem still attached. Blanch tomatoes for easy peeling. Peeling tomatoes isn't something I bother with unless absolutely necessary. If you leave the skin on, it ends up as little curls floating in the sauce.
Peeling also improves the texture of less than perfect tomatoes.
To keep tomatoes from getting waterlogged, I don't core them until after blanching. For the same reason, I don't bother to score the bottom of the tomato, as you see in some recipes. Cook the juices separately to intensify flavor Bring the tomatoes to a simmer in a wide pan, stirring occasionally with a wooden spoon, until they release most of their liquid but haven't lost their shape, about 5 minutes. Strain the juices into a saucepan, reserving the flesh. Boil the juices until concentrated in color and flavor and reduced by two-thirds.