Methode traditionnelle is the process of making sparkling wine, most famously Champagne, in which a still base wine undergoes a second fermentation inside the sealed bottle, then is aged on its spent yeast (the lees) before the yeast is removed and a small dosage of wine and sugar is added to set the final sweetness.
It is often confused with methode ancestrale, an older, simpler process used for Blanquette de Limoux, first documented in the 1530s at the Abbey of Saint-Hilaire in Limoux, in which a single fermentation is interrupted and finishes naturally in the bottle, without added yeast, sugar, or a dosage step. Methode traditionnelle, by contrast, deliberately triggers a second, separate fermentation for more control and consistency, and is the method behind Champagne, Cava, Franciacorta, and many English sparkling wines.
The extended aging on lees gives methode traditionnelle wines flavors of toasted bread, nuts, and citrus, along with a fine, persistent mousse (the wine's bubbles).