In Provence, France, a tian is a casserole of sliced vegetables as well as the round, shallow earthenware vessel in which the dish is baked. A classic tian showcases an assortment of summer produce, but here the focus is on tomatoes seasoned with garlic and herbs. We opt exclusively for plum tomatoes, which are firmer and drier than regular round tomatoes, and because they withstand long baking and yield deep, rich, concentrated flavor. Ripe, in-season tomatoes are best, of course, but even less-than-stellar fruits are good. We love this served warm with crusty bread and cheese, but the tomatoes can be refrigerated for up to a week and tucked into sandwiches or offered alongside grilled or roasted meats and seafood.