This is a refined version of twice-baked potatoes. I developed this recipe after playing around with making a smoked onion soubise (a rich white sauce made with onion purée) and wanting a way to show off the results. Although these potatoes happen to be vegetarian, they have an incredibly meaty quality from the smoky onions. This dish works any time you’d serve a baked potato—alongside a luxurious rib eye, a simple chicken breast, or even next to a salad for a comforting lunch.
I use two kinds of potatoes here because each one has different characteristics, and while the best variety for making fluffy mashed potatoes for the filling is russet, the best potatoes for making the delicate outer shells are Yukon Golds. As with the Potato Dumplings, you will need to use a potato ricer to get the necessary fluffy result. You will also need a pastry bag with a star tip (or a resealable plastic bag) for piping the filling into the shells.
- Yield: 4 Servings
- 4 large, waxy potatoes, such as Yukon Gold
- 3 tablespoons extra-virgin olive oil
- 0.125 teaspoon plus ½ teaspoon salt
- 2 tablespoons butter
- 2 cups smoked onions, roughly chopped
- 1 teaspoon salt
- ½ teaspoon freshly ground black pepper
- 1¼ cups heavy cream
- ½ cup water
- 1½ pounds russet potatoes
- 3 tablespoons plus ¾ teaspoon salt
- 1 egg yolk (see separating eggs), beaten
- ½ teaspoon freshly ground black pepper
- 1 teaspoon flaky finishing salt (optional)
- MAKE THE POTATO SHELLS Preheat the oven to 400°F. Place the Yukon Gold potatoes in a baking dish and toss with 2 tablespoons of the oil and the ¾ teaspoon salt. Pour water to a depth of about ¼ inch into the baking dish, then cover the dish with aluminum foil. Place in the oven and cook the potatoes until they can be easily pierced with a fork, 45 to 60 minutes. The potatoes should be just tender, not overcooked, and still slightly waxy. They need to hold their shape and their skins need to stay intact, so cook them carefully.
- Transfer the potatoes to a plate and allow them to cool for 10 to 15 minutes, then refrigerate for at least 1 hour or up to 8 hours. Do not peel.
- MAKE THE SMOKED ONION SOUBISE While the potatoes are cooking, in a small saucepan, melt the butter over medium heat. Add the smoked onions and season with the salt and pepper. Turn down the heat to low and sweat the onions for 4 to 5 minutes. Add the cream and water and simmer until the onions are completely soft and the cream has reduced and thickened slightly, 20 to 25 minutes.
- Transfer the onion-cream mixture to a blender and purée until very smooth, 1 to 2 minutes. Set up a chinois or fine-mesh strainer over a clean bowl and pass the onion purée through it to remove any particles, pushing down with a small ladle or rubber spatula.
- MAKE THE FILLING Place the russet potatoes and water to cover by 1 inch in a large saucepan over high heat. When the water starts to simmer, add 3 tablespoons of the salt, cover, adjust the heat to maintain a simmer, and cook until the potatoes are tender with a tiny bit of resistance at the center when pierced with a fork, 40 to 45 minutes. Turn off the heat but keep the potatoes in the hot water until they can be easily pierced with a fork, 5 to 10 minutes longer. Remove the potatoes from the water and let cool just until they can be handled, then use a kitchen towel to peel the skin from the still-warm flesh. Pass the potatoes through a potato ricer into a small bowl.
- Add 1 cup of the onion soubise to the riced potatoes and mix together with a fork. Add the egg yolk and mix well. Season with the remaining ¾ teaspoon salt and the pepper and set aside. Do not refrigerate.
- Once the waxy potatoes are chilled, slice them in half crosswise. Use a melon baller or small spoon to very gently hollow out as much of the potato as possible, discarding the scooped potato and leaving a layer of flesh about ⅛ inch thick attached to the skin for stability. Set the potato halves, hollow sides up on a baking sheet and set aside. The shells can be stored, lightly covered with plastic wrap, at room temperature for up to 4 hours.
- To test how the filling will bake up, preheat the oven to 400°F. Line a small baking sheet or baking dish with parchment paper and spoon a tablespoon or so of the filling onto the parchment. Bake until the edges of the filling begin to brown, 7 to 10 minutes. This will tell you if the filling will lose its shape and get runny when you pipe it into the potatoes. If it seems quite firm, add a few additional tablespoons onion soubise for flavor. If it is wet or runny, whip in another beaten egg yolk. Leave the oven on.
- To fill the potato shells, brush the inside of each shell evenly with the remaining 1 tablespoon oil, then dust the insides with the remaining ½ teaspoon salt. Place the filling in a pastry bag fitted with a large star tip (or fill a large resealable plastic bag with the filling and cut off one of the corners). Pipe the filling into the potato shells, filling them to about 1 inch above the rim.
- Place the filled potatoes on a baking sheet. Place the baking sheet on the center rack of the oven and bake until the edges of the filling are deep golden brown and the potatoes are piping hot, 15 to 20 minutes. If you have an extra potato, taste one to see if it needs a little finishing salt. Serve immediately.