Five-Star Cuisine for High Schoolers: Recipe for tuna with pickled watermelon and spring onion

The relatively new Léman Manhattan Preparatory School will enroll around 40 new boarding students this autumn, and they are in for a culinary treat. The school's Managing Director, Gerard Widder, promises a five-star experience, and no child could be disappointed by the efforts of Executive Chef Jenny Gensterblum. Around 50 realtors had the chance to try some of her original creations at a recent event, co-hosted with AVENUE Magazine, aimed at educating the property market about this extraordinary school. The food was quite simply the best I have tasted at any school. Ever. And Jenny has kindly agreed to share with New York Press readers her recipe for Seared Tuna with Pickled Watermelon and Spring Onion. It needs preparation time, but I promise you it's worth it?.   Seared Tuna with Pickled Watermelon and Spring Onion 16 Hors D'oeuvres    INGREDIENTS For the Pickled Watermelon, Mustard Seeds, and Peppers Pickling Liquid, divided: -2 cups water -1 cup apple cider vinegar -1/3 cup mirin -1/3 cup sugar -4  teaspoons salt   1 baby seedless watermelon, cut into 1 inch cubes ½ cup mustard seeds 2 serrano peppers, very thinly sliced   For the Spring Onion Puree 1 bunch of spring onions Olive oil Kosher salt 2 tablespoons butter   For the Tuna 6 oz bigeye tuna steak ½ teaspoon fennel pollen ½ teaspoon grated fresh ginger ½ teaspoon kosher salt Freshly cracked black pepper Grapeseed oil   To Finish Coarse sea salt Cilantro leaves   For the Pickles: 1. Heat the pickling liquid in a stockpot until it comes to a boil. Cool pickling liquid until room temperature. 2. Combine ½ cup of mustard seeds and 1 cup of the pickling liquid in a small stockpot. Simmer over low heat until the mustard seeds are tender and the liquid is mostly absorbed. Set aside to cool and refrigerate. 3. In a small ramekin, place the sliced Serrano peppers and add pickling liquid to just cover. Cover and refrigerate for at least 1 hour, or overnight. 4. Take cubed watermelon and place in a shallow dish. Pour the remainder of the pickling liquid over the watermelon. Cover and refrigerate for at least 1 hour and up to 12 hours.   For the Spring Onions: 1. Bring a large pot of salted water to a boil. 2. Meanwhile, trim the roots from your onions and rinse thoroughly. Separate the greens from the white bulbs. Chop the green portion into ½ inch pieces. Blanch the greens in boiling water for approximately 1 minute and shock in an ice bath. Remove greens once cooled and dry off with a kitchen towel. Process in the blender with olive oil until smooth, strain through a fine mesh strainer, discarding what does not pass through. Season to taste with salt and set aside. 3. Thinly slice the white portion of the spring onions. In a medium pan over medium heat, melt the butter. Add the onions and sauté until very tender, about 15-20 minutes. Process in the blender until smooth, season with salt, and set aside. If the mixture is dry, slowly drizzle in olive oil until smooth.   For the Tuna: 1. Slice the tuna steak into 1-inch wide strips. Mix together the fennel pollen, ginger, salt & pepper. Coat all four sides of the tuna steak with mixture and set aside. 2. Heat a large pan on high heat. When hot, coat the bottom of the pan with grapeseed oil. Sear all four sides of your tuna strips fairly quickly, for about 10 seconds per side. Immediately remove from the heat and refrigerate. 3. When cool, slice crosswise into at least 16 pieces. The width of the tuna and watermelon should be approximately the same size. Set aside.   To Finish & Assemble: 1. On your serving dish, place 16 cubes of pickled watermelon. Place a small dollop of the white spring onion puree on top of the watermelon. Gently place one slice of tuna. Spoon on some of green spring onion puree. Top with a bit of the pickled mustard seeds, one slice of Serrano pepper, and one cilantro leaf. Repeat with remaining watermelon and tuna. Finish with coarse sea salt and serve immediately.