POTATO, ONION AND TOMATO GRATIN

Potato, Onion and Tomato Gratin image

Number Of Ingredients 8

1/2 cup extra-virgin olive oil, plus extra for greasing the baking dish
1 3/4 pounds baking potatoes, peeled and cut into 1/6 inch thick slices
3 yellow onions, large, thinly sliced
6 plum tomatoes, cut into 1/6 inch thick slices
1 salt and freshly ground pepper
1/2 cup freshly grated Pecorino Romano
1/2 cup fresh bread crumbs
2 tablespoons fresh oregano, minced

Steps:

Preheat oven to 400 degrees
Generously oil the gratin dish. Make a layer of potatoes, a layer of onions and a layer of tomatoes in the baking dish, sprinkling each layer with a little of the salt and pepper and drizzling each layer with 1/2 tablespoon of the olive oil. Repeat with another layer of potatoes, onions and tomatoes, again sprinkling each with a little of the salt and pepper and drizzling each with 1/2 tablespoon of the olive oil.
Combine the Pecorino Romano, bread crumbs and oregano in a bowl.
Bake in the preheated oven for about an hour or until the potatoes are tender when pierced with a knife. After 50 minutes of cooking, top with the Pecorino Romano, bread crumbs and oregano and the remaining 5 tablespoons of olive oil. Continue cooking until the potatoes are cooked and the bread crumbs are brown and crispy. Serve immediately.
Prepare ahead...Cook the gratin up to 1 day ahead but to not add the bread crumbs, cheese and oregano. Allow to cool and store in the refrigerator, covered tightly. When ready to serve, remove the gratin from the refrigerator up to 2 hours ahead. Preheat oven to 400. Mix bread crumbs, cheese and oregano and spread evenly on top of the gratin. Spoon over the remaining olive oil and bake in the oven and back in the oven for about 20 minutes, until the topping is brown and crispy. Serve immidiately.