Mirin is a Japanese condiment containing about 14% alcohol. To make mirin, they mix together sauteed husked rice, cultivated rice and shochu (a distilled alcoholic beverage) and leave them to ferment for about 2 months.
Mirin produced following this process is called hon-mirin. This is what's known as "true" mirin. Another type is shio mirin, which also contains salt, and the 3rd kind is mirin-fu chomiryo, which translates as a "seasoning that tastes like mirin." It contains about 1% alcohol but provides the same aroma.
Mirin use is believed to have begun more than 400 years ago. Although it was used as a drink in the beginning, today it's used only in cooking because the beverage turns out too thick and sweet.
In essence, mirin is a kind of rice wine, similar to sake, but with a lower alcohol content and higher sugar content. Its sweet taste creates a pleasant contrast when used in tandem with salty sauces.
Mirin is a universal seasoning that goes well with just about everything - from meat and fish to vegetables and tofu. It's a nice complement to French fries and marinades and due to its sugar content it provides an eye-catching glaze to veggies, meat and fish.
When used in cooking, keep in mind that it has a strong taste, which is why it needs to be used in small amounts.