Soju is sometimes referred to as Korea's sake. The main ingredient for soju – known to Koreans as "a friend of life" - is rice as well as sweet potato/tapioca, barley, sugar and wheat.The clear liquid has a varied alcohol content: from 20 to 40 per cent and the taste is like a sweet vodka.
Soju is sometimes mistaken for cheongiu, the true Korean equivalent of sake. Cheongiu is a rice wine made through the fermentation of rice starch to sugars.
Soju is usually made by mixing pure ethanol with water and flavouring – if it's inexpensive, then you can bet it's made this way and it's usually called "diluted soju" while soju manufactured by distillation from grain is called "distilled soju."
Soju was born around 1300 AD at the time the Mongols invaded. The Mongols had the knowledge of alcoholic distillation. At the time, it was used as for medicinal purposes – to deal with stress (not a bad idea!).
Traditionally, the process begins with steamed rice cooled with cold water and then mashed with fermented glutinous rice. After a good stir, this blend is kept about a week to ferment and then boiled. A distilled alcohol forms on the surface after the mixture is dumped with cold water.
Soju is usually served straight and in a shot glass. In Korea, it's drunk in group gatherings and if a Korean says "one shot" – you gulp it all down.
As is Korean custom, you do not fill your own glass, others are expected to spot your empty glass and to fill it. Also, out of respect, you do not down your liquor in front of someone senior to you (in age and in professional terms). You should face away and drink.
Even though soju is meant to be drunk straight, Koreans have their soju cocktails. Often the liqueur is mixed with Sprite or syrup. Another cocktail involves mixing the drink with two parts Sprite and lemonade powder. Watermelon and apple soju are also popular drinks.
The largest producer of soju in Korea is Jinro and one of the most sought-after brands is Chamisul while in certain regions, white soju created by Muhak is tops.
Check out this website which rates different brands of soju: Korean Liqueurs.
Soju goes very well with many of Korea's spicy dishes including kimchi. Try it with a variety of Asian dishes – including Malaysian and Thai food - such as Green Chili Chicken, Spicy Indian Cauliflower, Singaporean Laksa, and Indian Chickpeas and Eggplant.
If you like, there are a host of other Asian cocktails to be had, including Singapore Sling.