Name: Potato and Tomato Gratin with Breadcrumb Topping
Total time: PLACEHOLDER
Cuisine: ItalianEurope
Ingredients: ¼ cup extra-virgin olive oil; 2 onions , halved and sliced thin; 1 tablespoon minced fresh oregano; Salt and pepper; 2 pounds russet potatoes; 3 pounds plum tomatoes , cored and sliced ¼ inch thick; 3 ounces Pecorino Romano cheese , grated (1½ cups); ¼ cup panko bread crumbs

Why This Recipe Works

In keeping with much of the local cuisine, this rustic dish is simple and intended to showcase the humble fruits of the region's rich soil as well as to provide field workers with a hearty, economical, and nutrient-dense lunch. A common incarnation involves baking layered rings of tomatoes, onions, and potatoes until tender along with some oregano for seasoning, a sprinkling of Pecorino for richness, and crumbled stale bread for texture. When we made the dish with field tomatoes, onions, and waxy potatoes (which are typical of the region), we found that the vegetables exuded an unappealing amount of moisture. Switching to plum tomatoes cut down on liquid and slowly sautéing our onions until golden brown not only drove away more water but added a layer of complexity. Using starchy russet potatoes improved matters further, as the cooked starch granules helped soak up the remaining juices.

Before You Begin

It is important not to slice the potatoes any earlier than the beginning of step 3 or they will begin to brown (do not store them in water; this will make the gratin bland and watery). Slicing the potatoes ⅛ inch thick ensures they cook evenly and relatively quickly, so the tomatoes don't break down too much in that time; use a mandoline or a food processor fitted with an ⅛-inch-thick slicing blade.

Instructions

Heat 2 tablespoons oil in 12-inch skillet over medium heat until shimmering. Add onions, 1 teaspoon oregano, ½ teaspoon salt, and ¼ teaspoon pepper and cook, stirring frequently, until soft and golden brown, 15 to 20 minutes.

Adjust oven rack to upper-middle position and heat oven to 400 degrees. Grease 13 by 9-inch baking dish. Combine remaining 2 teaspoons oregano, ½ teaspoon salt, and ½ teaspoon pepper in bowl.

Peel and slice potatoes ⅛ inch thick. Shingle half of tomatoes evenly in prepared dish, then sprinkle with ½ cup Pecorino. Shingle half of potatoes on top, then sprinkle with half of oregano mixture. Spread onions over potatoes, then shingle remaining potatoes over top, followed by remaining tomatoes. Sprinkle with remaining oregano mixture and drizzle with remaining 2 tablespoons oil.

Bake, uncovered, for 1 hour. Sprinkle with remaining 1 cup Pecorino, then panko, and bake until top is well browned and potatoes are tender (paring knife can be slipped in and out of potatoes with little resistance), about 20 minutes. Let cool for 30 minutes before serving.