Potato-Tomato Gratin

This delectable Potato and Tomato Gratin recipe is a comforting and flavorful dish that brings together the earthiness of russet potatoes and the brightness of sweet plum tomatoes. The combination of caramelized onions, garlic, thyme, and chopped kalamata olives elevates the gratin’s taste, while the bubbling Gruyère cheese on top adds a rich and nutty finish. The key to achieving the perfect texture lies in using thinly sliced potatoes and plum tomatoes, allowing for even cooking and avoiding excess moisture. This gratin is a delightful side dish or a hearty main course that will satisfy your taste buds and warm your soul. It serves 4 to 6, making it perfect for sharing with family and friends.

SERVES 4 TO 6

INGREDIENTS:

• ½ cup pitted kalamata olives, chopped
• 3 pounds plum tomatoes, cored and sliced ¼ inch thick
• 2 pounds russet potatoes, peeled and sliced ⅛ inch thick
• 2 teaspoons minced fresh thyme
• 8 ounces Gruyère cheese, shredded (2 cups)
• 2 tablespoons olive oil
• 2 large onions, thinly sliced
• 1 teaspoon salt (divided)
• ½ teaspoon pepper (divided)
• 2 garlic cloves, minced
• ¼ cup water

INSTRUCTIONS:

1. Adjust the oven rack to the upper-middle position and preheat the oven to 400 degrees Fahrenheit (200 degrees Celsius). Grease a 3-quart gratin dish (or 13 by 9-inch baking dish) and set it aside.
2. In a 12-inch skillet, heat the olive oil over medium heat until shimmering. Add the thinly sliced onions, ½ teaspoon of salt, and ¼ teaspoon of pepper. Cook, stirring frequently, until the onions become soft and golden brown (approximately 15 to 20 minutes).
3. Stir in the minced garlic and cook for about 30 seconds until fragrant. Add the water and continue cooking until the water is nearly evaporated, scraping up any browned bits from the bottom of the skillet. Once the water has evaporated, stir in the chopped kalamata olives. Set the onion mixture aside.
4. Shingle half of the sliced tomatoes in an even layer at the bottom of the prepared gratin dish. Then, layer half of the sliced potatoes over the tomatoes and sprinkle with 1 teaspoon of minced thyme, ½ teaspoon of salt, and ¼ teaspoon of pepper. Next, evenly spread the onion mixture on top.
5. Repeat the layering process with the remaining potatoes, tomatoes, minced thyme, salt, and pepper.
6. Bake the gratin, uncovered, in the preheated oven for 1 hour.
7. After an hour, remove the gratin from the oven and sprinkle the shredded Gruyère cheese evenly over the top.
8. Return the gratin to the oven and continue baking until the cheese becomes browned and bubbly, and the potatoes are completely tender (approximately 25 to 30 minutes).
9. Let the gratin cool for about 30 minutes before serving. This waiting period allows the flavors to meld together and ensures a delightful eating experience.

TIPS:

• Choose the Right Tomatoes and Potatoes: Opt for plum tomatoes for this recipe, as they release less juice, preventing the gratin from becoming too watery. Russet potatoes are the ideal choice due to their higher starch content, which helps them soak up the tomato juices and maintain the gratin’s consistency.
• Evenly Sliced Potatoes: Thinly slicing the potatoes is essential for ensuring they cook evenly throughout. Use a mandoline, V-slicer, or the slicing disk on a food processor to achieve uniformly thin slices.
• Caramelizing Onions: Take the time to caramelize the onions until they become soft and golden brown. This process enhances their sweetness and adds depth of flavor to the gratin.
• Layering the Ingredients: Layer the tomatoes and potatoes evenly in the gratin dish, alternating with the onion mixture, and sprinkling each layer with thyme, salt, and pepper. This ensures that the flavors are distributed throughout the gratin.
• The Baking Process: Bake the gratin uncovered to allow any excess water to evaporate, resulting in a moist yet not waterlogged dish. The final touch of Gruyère cheese on top adds a delightful nutty flavor and gives the gratin a beautiful bubbly finish.

Serve this scrumptious Potato and Tomato Gratin as a delightful side dish or a comforting main course, and watch it disappear from the table with smiles of satisfaction. Enjoy this hearty and flavorful dish with your loved ones on any occasion!