The human body may be a furnace that burns whatever you put in it, but if you have experience tending the family's fire place, you know some things burn more cleanly or quickly than others. To maximize the heat you can get out of your furnace (aka, get the most from your body during training and racing), it is good to know what burns best in the time you have.
Velonews has an article, The right food for bike racing and training, that gives some tips for what types of food are often best depending on how much time you have before a workout or race. Some examples may or may not fit your tastes, but the general concepts shared should help give you good ideas of foods you like and be a reminder that you need some fuel in the furnace to make your engine go.