Chop or slice garlic with a knife.
Put the garlic in the steamer.
Put the rock sugar in a steaming cup.
Add the right amount of water, which is about two-thirds of the height of the cup.
Cover it to prevent water from dripping in when steaming (fasten it with a small dish if using a bowl).
Put the steaming cup in the pot to steam. After the fire boils, steam on low heat 15 minutes.