To effectively boil eggs in steam, it typically takes around 15 to 20 minutes. This duration ensures that the eggs are fully cooked without overcooking, which can lead to rubbery textures. The steam method is a healthier alternative to traditional boiling as it requires less water and can preserve more of the egg's nutrients.

The reason for this time frame lies in the heat transfer process. When eggs are placed in a steamer, the steam gradually cooks them from the outside in. The heat is more gentle compared to direct boiling, which can cause the egg whites to become tough and the yolks to overcook. According to the United States Department of Agriculture (USDA), eggs should be cooked to an internal temperature of 160°F (71°C) to ensure safety and proper doneness. Steam cooking allows for a more controlled and even heat distribution, leading to a tender and well-cooked egg. Additionally, the steam method is more energy-efficient and can save time, as it doesn't require the water to reach a rolling boil before adding the eggs.