Root vegetables are best when put on to cook in cold water seasoned with salt, sugar, and a chunk of butter. Starting them to cook in cold water lets them heat from the inside out as the water warms. Cooked in this way their outside area is not overcooked before they are done in the middle. All parts are done at the same time.
Vegetables that are grown underground are usually round and fat, or round and long. They may be cooked whole, but in French cooking they are usually cut into quarters, eighths or pieces, then trimmed to an exact shape, and cooked. These shapes are: