Makes 6-8 servings. Difficulty
2 teaspoons olive oil 1 large leek, white & pale green parts only (washed thoroughly), sliced thin 1 teaspoon fresh thyme, chopped
1-1/4 pounds red potatoes, unpeeled, cut into 1/4 inch slices 1/2 teaspoon kosher salt 1 Tablespoon olive oil 2 teaspoons fresh rosemary, chopped
1-1/4 pounds ripe tomatoes, sliced 2 Tablespoons fresh basil, slivered 1-3/4 cup gruyere cheese, grated 1/2 teaspoon kosher salt and freshly ground black pepper to taste
In a medium skillet, heat 2 teaspoons olive oil over medium heat. Add leeks and sauté, stirring frequently, for about 10 minutes or until limp and lightly browned. Set aside and let cool.
Toss cooled leeks with fresh thyme.
Meanwhile, in a medium saucepan cover potatoes with cold water; adding a generous pinch of salt to water. Bring to a gentle boil and cook for about 5 minutes or until just barely tender. Drain and rinse under cold water until cool. Pat dry.
In a large bowl toss potatoes with 1 tablespoon olive oil, 1/2 teaspoon salt and rosemary.
Preheat oven to 375°F.
Grease a 2 quart shallow gratin dish.
Starting at one end of baking dish, lay a row of tomatoes across botton, overlapping slightly as you go. Sprinkle with half the basil. Cover with a generous sprinkling of gruyere. Layer potato slices over tomato and cheese layer. Sprinkle potato layer with cheese. Repeat process, starting with tomatoes, sprinkle with remaining basil, followed by gruyere then one more row of potatoes and finally topping with remaining gruyere. Sprinkle top of gratin with leeks. Season top with about 1/2 teaspoon salt and freshly ground black pepper.
Bake gratin until it is well browned all over and juices have bubbled for awhile and have reduced considerably, about 60-65 minutes. Let cool for at least 15-20 minutes before serving.