This plant is a volunteer in my garden every summer. Known sometimes as Beefsteak Plant in English, but also by its Japanese name of Shiso, it is a member of the mint family. There are 2 species of shiso, green, and red. Anyone who has had sashimi will know green shiso as its leaves are the bed on which the sashimi lays. It is also used in salads, cooked as tempura etc. Red Shiso, pictured above, is used to give umeboshi and pickled ginger its distinctive purple color. It also makes a fragrant, tasty lemonade.
Boil the leaves for about 5 minutes, strain, add sugar to taste and then let cool. Add citric acid (lemon juice) and store in the fridge.