‘Flambé’ is a French culinary term meaning ‘to pour spirits over and ignite’, thus enhancing the flavour. Not only does it make for a great show, the flame toasts the food and helps brown it. If the dish contains sugar, this will caramelise it.
You can use brandy, whisky, vodka (basically any ‘hard tack’ high in alcohol) and liqueuers. While liqueurs can be flambéd alone, but for best effect mix with a stronger spirit such as rum or brandy.
Generally, make sure the food is very hot, and heat the spirit in a tiny saucepan until hot but not boiling before adding to the dish. Use a long match or lighter to ignite it, tilting the pan away from you as you light the alcohol. The liquor should always be added at the very last moment and lit as quickly as possible to avoid the liquor soaking into the food. Let the alcohol burn off enough and leave the flame to go out naturally so the flavour does not overpower the dish.