In a very large nonstick skillet, heat 2 tablespoons of the oil. Arrange half of the dumplings in the pan, pleated edge up. Cook over high heat until the bottoms are lightly browned, about 2 minutes. Add 1/2 cup of water to the skillet, cover and cook until the water is evaporated and the dumplings are cooked through, about 5 minutes longer. Uncover and cook until the bottoms are well browned, about 1 minute longer. Transfer the dumplings to a plate. Cook the remaining dumplings in the remaining oil and serve.