It's named after a Crimean War battle in Sevastopol — Swiss mercenaries who fought there came home and started frying cheese to commemorate the siege.
Chunks or slices of cheese are coated in a light batter or breadcrumbs and deep-fried until molten inside and crisp outside, served hot with bread and a glass of white wine. Stands around Lake Geneva's shoreline villages and markets sell them by the skewer or plate.