Lotus seeds are difficult to cook thoroughly because their skin has a layer of cutin that thickens over time, making it hard for them to absorb water and expand. This is especially true for lotus seeds from the previous year. Additionally, lotus seeds should only be soaked for a short time (about 10 minutes) or not at all at all, as prolonged soaking makes them harder to cook. There are two methods to cook lotus seeds until they are tender.
Method 1
Soak the lotus seeds in hot alkaline water at a ratio of one part alkali to ten parts water. After the alkali has dissolved, add the lotus seeds and soak for about an hour. Knead the seeds with your hands until their skins peel off. Then, transfer them to hot water to allow the pulp to expand. After this, they will become tender with just a brief boil.
Method 2
First, place the lotus seeds in the freezer for a day. Then, cook them by bringing them to a boil for 5 minutes, turn off the heat, and let them steep in the pot. Once the pot has cooled slightly, bring it to a boil again. Repeat this process three times. If you have a pressure cooker, you can also place the seeds in it, bring to a boil over high heat, then reduce the heat and simmer slowly for about 30 minutes.
It is worth noting that adding sugar too early is not advisable, as it will prevent the lotus seeds from becoming tender. If sugar is added prematurely, the moisture inside the seeds will be drawn out, causing them to become shriveled and difficult to cook. Therefore, the best time to add sugar is after the lotus seeds have been cooked until tender.