Petrossian's Executive Chef, German Calle, quickly sears the fish, then finishes it in the oven, giving it a beautiful brown crust. He serves it atop tender mushrooms and Brussels sprouts and, highlighting the company's signature product, good-quality caviar, tops it with a caviar-infused beurre blanc.
For the beurre blanc:
Combine the first six ingredients in a saucepan over high heat and reduce until the wine has nearly evaporated. Then add the fish stock and reduce until nearly evaporated. Add the cream and reduce by half, turning the heat to low when it begins bubbling.
Strain the mixture. Discard the solids and put the hot liquid into the blender and puree. Slowly add the cubes of butter to the working blender. Season and reserve in a warm place.
For the mushrooms and Brussels sprouts:
Place a pot of salted water over high heat and bring to a boil. Prepare an ice bath.
Meanwhile, place a sauté pan over high heat until very hot and then add oil. Cook the mushrooms in batches, placing them in a single layer in the hot pan. Add a pinch of shallots, garlic, a sprig of thyme and salt and pepper. Sauté until slightly brown and then turn over to the other side and repeat the process. Repeat again with the remaining mushrooms. Reserve.
When the water has reached a boil, add the Brussels sprouts and blanch, cooking until just tender. Then remove with a slotted spoon and immediately place into the ice bath to cool.
For the fish:
Preheat oven to 400 degrees.
Put an oven-proof sauté pan over high heat and add a little oil, using two pans if necessary. Season the sturgeon and place in the very hot pan(s). Brown the presentation side first, then flip and place in the preheated oven until cooked through, about 8-10 minutes depending on thickness of the fish.
Meanwhile, in another pan, over medium heat, sauté the reserved mushrooms and add the blanched Brussels sprouts. Season with salt and pepper. Place the cooked sturgeon on top of the mushroom fricassee. Add the caviar to the sauce and combine. Pour the caviar-beurre blanc over the fish and garnish with chervil.