1 scallion, trimmed and sliced very thinly at an angle
Directions
Make the sweet-and-sour tomato sauce: In a small saucepan over medium-high heat, combine the ketchup, vinegar, sugar and soy sauce. Bring to a simmer, stirring occasionally, until the sugar dissolves, 2 to 3 minutes.
In a separate bowl, whisk together the cornstarch and water. Stir into the ketchup mixture and continue to simmer until thickened, 2 to 3 minutes. Season with salt. Remove from the heat and allow to cool to room temperature. Makes ¾ cup.
Make the oyster omelet: In a small bowl, whisk the eggs and season with salt and pepper. Set aside.
In a small bowl, stir together the cold water and sweet potato starch. Set aside.
In a medium nonstick skillet over high heat, add 2 tablespoons of oil. When the oil is very hot and begins to shimmer, add the oysters to the pan. Cook until most of the liquid has evaporated and the oysters start to firm up, 1 to 2 minutes. Pour the egg mixture over the oysters and cook until just until barely set on the bottom, 30 to 40 seconds. Pour the sweet potato slurry over the egg and, using a rubber spatula, scrape the egg mixture toward the center to form a round shape about 5 to 6 inches in diameter. Cook, loosening around the edges, until golden brown on the bottom, 3 to 4 minutes. Top the omelet with the celery leaves and place a large plate over the skillet and invert the omelet.
Heat the remaining oil in the pan and slide the omelet back into the pan, brown side up, and continue to cook until light golden brown on the bottom, 3 to 4 minutes.
Slide the omelet onto a serving dish. Drizzle it with the sweet-and-sour tomato sauce and garnish with the scallions. Serve.