Beetroot used to be difficult to find in Hong Kong but now even wet markets are starting to carry them.
What are they? Beetroot is (you guessed it) a root vegetable. The tops are also edible and are, appropriately, called beet greens. Most people think of beetroot as having a deep, rich colour ranging from ruby red to deep purple, but varieties come in several different colours, including pale pink, gold and white-and-pink striped.
What are the differences? Flavour differences are largely theoretical in Hong Kong unless you're growing them yourself because we seem to get only the dark red or purple types, which aren't usually divided into varieties. Reportedly, golden beets have a milder flavour than those that are red and purple.
How to choose: pick firm specimens with no cracks or soft spots. The skin should be unwrinkled.
How are they available? In cans, cooked and peeled (packaged in vacuumed bags and sold in the refrigerated vegetable section of supermarkets), frozen, in jars (usually pickled) and fresh. Pre-cooked and peeled beetroot is convenient but tends to be very tender - fine if you're using it in soups and purees, but not so good if you want to cook it further but still need to maintain some texture. Unprepared beetroots have the unfortunate drawback of 'bleeding' colour as they're being peeled. It doesn't matter if you're peeling them raw or cooked; they'll stain your hands (consider wearing clean kitchen gloves) and cutting boards. Beetroot crisps are available as a delicious yet expensive alternative to potato crisps.
What else? The sugar beet is a large, off-white variety. It is sliced and pressed to extract the liquid, which is then purified and cooked to make different types of sweeteners, including molasses, syrup and crystallised sugar.