Summer promises a bounty of sun-kissed vegetables—a cornucopia of tomatoes, peppers, squash, and eggplant that beg to be put to use. This is not a problem. The trick is to lean in and rely upon recipes that embrace and celebrate the abundance of produce. One tried-and-true dish that does so is ratatouille. Ratatouille is the southern French staple that handily combines all of the garden’s goodies layered in a terrine or simmered in a chunky, aromatic stew. In the past, I never followed a recipe for ratatouille—I simply winged it and gathered whatever provencal vegetables were on hand, then sautéed and simmered them together in a tomato-streaked stew. The results were usually thick and warm with a saucy compote consistency. Lately, however, I have taken a fresher, recipe-driven route, thanks to the chef Alice Waters. In her ratatouille recipe, Waters cooks each vegetable individually as she slowly combines them into …