Nantucket Bay Scallops and Soba Gnocchi with Celery Root Foam

Nantucket Bay Scallops and Soba Gnocchi with Celery Root Foam
Recipe courtesy of:
Chef: Takashi
Serving for 4 People 
1 large Idaho potatoes 
2 tablespoons of grated Parmesan cheese
½ teaspoon of extra-virgin olive oil
½ lightly beaten egg
½ teaspoon of kosher salt
Pinch of white pepper
¼ cup of all-purpose flour, plus more for dusting
½ cup of buckwheat flour
2 tablespoons of vegetable oil
Celery Root Foam: 
1 tablespoon extra-virgin olive oil
½ white portion of 1 leek, rinsed well and thinly sliced
¼ onion, thinly sliced
2 cloves garlic, minced
1 ¾ teaspoons kosher salt
1 ½ cups cubed celery root
4 cups of water
¾ cup of half-and-half
1 cup of skim milk
1 tablespoon of unsalted butter
Pinch of white pepper
¼ cup of extra-virgin olive oil
2 cups of Black Trumpet Mushrooms 
½ teaspoon of kosher salt
1 tablespoon of unsalted butter
1 tablespoon of minced garlic
1 tablespoon of minced shallot
½ cup of heavy cream
2 tablespoons of grated Parmesan cheese
1 tablespoon of minced parsley
32 Nantucket Bay Scallops
Pinch of salt and white pepper
To prepare the gnocchi, preheat the oven to 400 degrees Fahrenheit. Using a fork or the tip of a paring knife, poke several small holes in the potato and place it on a baking sheet. Bake the potatoes for 1 ½ hours, or until the potato is very soft to the touch (it should give easily when pressed).
Meanwhile, begin the celery root foam. Place a saucepan over medium heat. After 30 seconds, add the olive oil and let it heat for 1 minute, or until it’s hot but not smoking. Add the leek, onion, garlic, and ¼ teaspoon of the salt. Decrease the heat to low and cook, stirring often, until the vegetables are translucent, about 5 minutes. Add the celery root and cook for 2 minutes longer. Add the water and bring just to a boil before decreasing the heat to medium-low. Simmer until the celery root becomes soft, about 30 minutes. Remove the saucepan from the heat and let it sit at room temperature until mostly cool, about 15 minutes.
To finish the foam, combine the half-and-half, skim milk, butter, remaining 1 ½ teaspoons salt, and white pepper in a blender. Add the cooled celery root mixture and blend on high speed until smooth. Strain the sauce through a fine mesh sieve into a pot. Heat over low heat until the liquid begins to simmer, and then turn off the heat and cover to keep warm until ready to use, or if making in advance, cool and reheat later.
To prepare the gnocchi, split the potato in half while still hot. Use a spoon to scoop out the inside, discarding the skin. Grind the potato through a food mill or ricer (you can also use a fine-mesh strainer, but don’t use a food processor) and combine it with the Parmesan cheese, olive oil, egg, salt, and pepper. Add the all-purpose and buckwheat flours until you have a smooth, creamy texture, being careful not to overwork the dough.
Dust a work surface with all-purpose flour and divide the dough into 4 portions. Gently roll one portion of the dough on the counter to create a long rope ½ inch thick. Cover the remaining dough with a dry towel.
Lightly pinch the rolled dough between your thumb and index finger. Use a paring knife to cut the dough into 1-inch-long pieces. Each piece should resemble a small pillow (the literal translation of the Italian word gnocchi).
Repeat with the remaining dough until all has been used.
Prepare an ice bath and bring a large pot of heavily salted water (1 gallon water to ¼ cup salt) to a boil over high heat. Add one-fourth of the gnocchi and cook until the gnocchi have risen to the surface, 1-2 minutes (they should be cooked through but still hold their shape).
Remove the gnocchi from the water and submerge in the ice bath. Drain once to cool. Repeat with the remaining gnocchi. Once all the gnocchi have been cooked, lightly toss them with the vegetable oil and refrigerate until ready to use.
To assemble the dish, place a large sauté pan over high heat. Add 2 tablespoons of the olive oil. After 30 seconds, add the mushrooms and salt. Cook until each side of the mushrooms are lightly browned, about 4 minutes, then add the butter. Once melted, add the gnocchi, garlic, and shallot. Cook until the gnocchi are lightly brown. Add the cream and Parmesan cheese. Decrease the heat to low and cook until the sauce has thickened. Stir in the parsley and set aside.
Heat another large sauté pan with the remaining 2 tablespoons olive oil. Season the scallops with a pinch each of salt and pepper, and then add to the hot pan. Cook for 1 ½ - 2 minutes, until the bottoms of the scallops have browned, then turn over and decrease the heat to low. Cook 2 - 2 ½ minutes longer or until scallops are cooked to medium.
In a saucepan, heat the foam mixture to a simmer, and then transfer it to a tall, narrow container or pot. Use an immersion blender to “foam” the sauce, which will create a layer of bubbles on the surface.
To serve, divide the gnocchi and sauce among 4 shallow bowls. Top each with 4 scallops and ¼ cup foam.