When Perfect Potato Gratin Meets Silky Tuna Tartare
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- Mandoline
INGREDIENTS
- 2 ripe tomatoes, grated
- ½ cup/120 grams sour cream
- 1 teaspoon dukkah spice, optional
- 3 hot peppers
- 5 garlic cloves
- 1 tablespoon fresh zaatar leaves
- ¼ cup olive oil
- Pinch of salt
Gratin:
- 5-6 large gold potatoes, peeled
- 1 teaspoon salt
- 3 tablespoons olive oil
Tartare:
- 7 ounces/200 grams sushi-grade tuna, finely chopped
- 1 tablespoon olive oil
- ¼ teaspoon salt
- 2 tablespoons chives, finely chopped
INSTRUCTIONS
- Preheat the oven to 320°F (160°C) with a convection setting if available. Slice the potatoes paper-thin using a mandoline. Line a baking sheet with parchment paper, drizzle with olive oil, and sprinkle with salt. Arrange a few layers of potatoes in the pan, repeating with more olive oil and salt every few layers. Press the slices tightly together to prevent gaps.
- Bake for about 1½ hours until the top is golden and crisp. If possible, place another baking tray on top while baking to apply gentle pressure. Once out of the oven, cover with a clean kitchen towel and weigh it down with cans or another heavy object. Let rest in the refrigerator overnight.
- The next day, cut the gratin into small squares or rectangles. Heat a thin layer of oil in a skillet over medium heat and fry the pieces on both sides until golden, about 2 minutes per side. Immediately season with salt. For extra brightness, grate fresh lemon zest over the top. Let cool slightly before serving.
- For the tuna tartare, mix the chopped tuna with olive oil, salt, and chives in a bowl. Spoon onto a serving plate.
- Season the grated tomatoes with salt. Serve the sour cream plain or topped with olive oil and dukkah. To make the spicy sauce, blend the hot peppers, garlic, zaatar leaves, olive oil, and salt in a food processor or shaker until smooth. Serve everything together, allowing everyone to combine flavors as they like.
MY NOTES
FAQ
What is the secret to making a perfect potato gratin that holds its shape?
To achieve a perfect potato gratin that holds its shape, the key is to slice the potatoes thinly and arrange them tightly in layers. This ensures the gratin cooks evenly and remains firm when cut. Use starchy potatoes like russets, which break down during cooking, creating a creamy texture. Another important step is to apply pressure while the gratin cools, which helps the layers bind together. After baking, pressing the gratin with weight (like canned goods) will help it hold its shape as it cools in the fridge. This method prevents it from falling apart when sliced.
Can I make potato gratin ahead of time and reheat it?
you can make perfect potato gratin ahead of time. Prepare the gratin up to the point of baking, then cool it to room temperature and refrigerate overnight. When ready to serve, reheat the gratin in a preheated oven at 350°F (175°C) for about 20-30 minutes, until heated through. Alternatively, if it’s already baked, cover it with foil to retain moisture and reheat for about 15-20 minutes. Reheating will soften the gratin slightly, but pressing it after baking and chilling will help maintain its shape when sliced and served.
What type of potatoes work best for a perfect potato gratin?
For a perfect potato gratin, starchy potatoes are ideal because they break down during cooking, releasing their starch and creating a creamy, smooth texture. Russet potatoes are the most common choice, but Yukon Golds can also work well if you prefer a slightly firmer texture. Waxy potatoes like red or new potatoes aren’t ideal because they hold their shape too well and don’t release enough starch to create the creamy consistency typical of a gratin. The key is to choose a potato that will soften and release its starch, blending seamlessly into the cream.
Why does my potato gratin fall apart when I slice it?
A potato gratin can fall apart for several reasons. If the potatoes are sliced too thickly, they may not cook evenly, leading to a broken texture. Additionally, if the gratin is not tightly packed or compressed enough during cooking and chilling, the layers can separate when you attempt to slice it. Another common cause is undercooking the gratin. Ensure it’s fully cooked before chilling and pressing it. After baking, it’s crucial to let the gratin cool and chill in the fridge for several hours or overnight, which allows the layers to set and hold together when sliced.
Can I use sweet potatoes instead?
While you can use sweet potatoes for a gratin, the result will differ from the classic perfect potato gratin. Sweet potatoes are sweeter and denser than regular potatoes, and they don’t release the same amount of starch. As a result, the gratin will be less creamy and more firm. If you decide to use sweet potatoes, be sure to adjust the seasoning to balance their sweetness, and consider adding more cream or cheese to create a smoother texture. A mix of both regular and sweet potatoes can also yield an interesting flavor and texture balance in your gratin.
Is it necessary to chill the gratin overnight?
Chilling the gratin overnight is recommended for the best results, as it helps the layers set and makes it easier to slice cleanly. The chilling process allows the gratin to firm up, ensuring that it holds together when sliced. However, if you’re short on time, you can chill it for at least 4 hours to allow some firming before serving. Skipping the chilling step may result in a looser gratin that could fall apart when sliced. If you’re in a rush, you can press it with weight for a short time to help it hold together, but the texture won’t be as perfect.
