Crack 3 eggs in a liquid measuring cup and note the volume. Pour the eggs into a large bowl, add salt, and beat for at least 1 minute. Now measure out water at the same volume as the eggs, and add it to the bowl. Do the same with the broth. Whisk in the sesame oil, and make sure everything's well combined.
Place 4 empty ramekins in a steamer over high heat. Be sure the water will not bubble and touch the ramekins during steaming. Once the water boils, turn the heat down to a slow simmer. Then, divide the egg mixture into the ramekins, pouring it through a fine mesh strainer.
Cover the steamer, turn up the heat to high, and steam for 3 minutes. After 3 minutes have elapsed, shut off the heat but keep the steamer covered. Let stand for 14 minutes with the lid firmly covered. Remove from the steamer, sprinkle with scallions, and serve.