Zucchini and Tomato Tart

For the beauty of the presentation, the slices of tomato should remain intact and undeformed. To peel the tomatoes, use a small, sharply pointed paring knife, cut out a cone at the stem end of each to remove the core, then slit a cross in the skin at the bottom or flower end and plunge them into a pot of boiling water. Drain immediately and slip off the skins, pulling the corners at the cross, between thumb and knife blade, toward the stem ends. To seed the tomatoes, slice each in half hori