Bain-Marie method with Tokkuri.
It is based on the bain-marie method, which involves partially submerging a sake vessel in hot water and then heating the sake until its temperature is reached, as the sake inside continues to heat steadily, evenly, and gradually. As a traditional method of serving sake, tokkuris are ceramic vessels with a vase-like shape used for serving sake.
Put the tokkuri in the pot and fill it with water until it covers about two-thirds of the tokkuri. Remove the tokkuri and heat the water to a boil. Once boiling, remove the pot from the heat. Place the tokkuri in the hot water and allow it to sit there until the sake reaches the ideal temperature.
The hot water helps to open up the sake and bring out the aromas and flavours, allowing for the best experience when drinking. The tokkuri also helps to keep the temperature consistent and prevents the sake from becoming too hot.
Sake can be heated in a microwave for faster heating or with insufficient equipment. This method heats sake much faster than the Tokkuri method but sacrifices control and can damage the sake a little bit. The container that holds the sake also heats unevenly, causing heat pockets in the sake.
Using a 600W or 1000W microwave, heat 100ml of sake for 20 or 15 seconds with a plastic cover to retain aromas. Once done, carefully remove the hot vessel and stir the sake inside to help redistribute the heat. Cover again with plastic wrap and heat for another 15 or 20 seconds.
The high wattage of the microwave helps to quickly heat the sake, while the plastic wrap helps to retain the aromas from the sake that would otherwise be lost. The stirring also helps to even out the heat and ensure that the sake is heated evenly.