When boiling water to steam vegetables, it is generally recommended to turn down the heat once the water has reached its boiling point (100°C or 212°F at sea level). This is because you want to maintain a steady but gentle flow of steam to cook the vegetables without overcooking them or causing excessive evaporation.
While there isn't a specific ideal temperature for steaming vegetables, the goal is to maintain a temperature that allows the vegetables to cook evenly and retain their texture and nutrients. Typically, keeping the heat at a medium to medium-low setting is sufficient to generate enough steam for cooking while preventing the water from boiling vigorously.
The steam itself will be hotter than 100°C (212°F) as it transfers heat to the vegetables, but the temperature of the surrounding environment doesn't need to be excessively high. You can adjust the heat as needed during the cooking process to ensure a gentle and consistent steaming temperature.
It's important to note that cooking times can vary based on the type and size of the vegetables, so it's advisable to follow specific recipes or guidelines for the vegetables you are steaming to achieve the desired results.