When people think of radishes, they usually think of the quick growing "spring radishes," like french breakfast, easter egg or tapering icicle type varieties. Easy to grow and easy to eat, usually eaten raw, they are juicy and crunchy addition to many quick snacks and appetizers. The world of radishes is far more extensive than these. Everywhere in the world, radishes of all shapes and sizes are grown and prepared in vastly different ways. The winter radishes all have one thing in common. They are very dense in order to survive harsh growing climates, and their flavor is much stronger than spring varieties. They are generally treated in one of two ways, braised until tender to mellow their sharp flavor, or grated and served as a condiment to highlight their strong and sometimes spicy nature.
Some of these radishes are known by many names. The bleeding heart radish or watermelon radish has too many monikers to list, but seems to be derived from one of the many softball sized asian radishes. It has a beautiful spectrum of color, and is sometimes thinly shaved raw to show it's beauty, but this radish is quite dense for such uses, and thin slices should at least be soaked in cold water before using them raw. It does maintain its colors after being braised, although the color does fade. There are also varieties that have all red skin and flesh, resembling a chioggia beet.
The so-called Spanish black radish is especially tolerant of cold climates, and unlike most winter radishes, it stores well after harvesting. It has a very strong flavor reminiscent of horseradish, and often used in the same way. This root vegetable is common among eastern European cultures. It can be grated and mixed with sour cream or rendered goose fat to spread on dense pumpernickel or rye. It makes a good pickle, or braised until tender with cream or butter.
The Chinese daikon radish is familiar to Americans, but there are many more giant winter radishes of different shapes and sizes. The Chinese probably love radishes more than any other culture, and as a result, they have cultivated the most variety. As with the black radish, it is usually either pickled, braised until tender and served as an accompaniment, or grated and used as a condiment mixed with citrus peels, herbs or chiles. The daikon is one of the most mellow, and a good place to start if you are trying something new with winter radishes.