Rinse Red shiso leaves well.

In a pot (do not use aluminum), boil water.

Then add the shiso leaves and simmer for 7 to 8 minutes, stirring occasionally with chopsticks.

Line a colander with a paper towel, then strain the juice and return to the pot.

Add sugar to the pot, then heat. The juice would be dark red.

Add vinegar and the color would be more reddish.

It's ready after coming to a boil. Skim any scum that rises. Drink after cooling.