If you want a deliciously " melts-in-the-mouth" leche flan, be sure to strain the mixture in a fine strainer or clean thin cloth once or twice.
For a successful steaming, put the molds or llanera with the mixture while water is boiling. Make sure the fire is in constant level while steaming the leche flan. Don't attempt to lower the the heat while the steaming process is in progress. This will affect the consistency of the leche flan. If it's overdone, it may appear whitish and lo! instead of a leche flan, it will taste like scrambled eggs in molds.
You can tell when the Leche Flan is cooked by inserting a toothpick or knife while steaming it. If it comes out clean, it is cooked.