Amontillado is a particular dry style of Sherry, characterised by being darker in colour than a Fino, but lighter than an Oloroso Sherry. It is named for the 'Montilla' region of southern Spain, where the style originated in the 18th century, although the name 'Amontillado' is sometimes used commercially as a simple measure of colour to label any Sherry lying between a Fino and an Oloroso style.
An Amontillado Sherry begins life as a Fino, fortified to approximately 13.5% alcohol with a cap of 'flor' yeast limiting its exposure to oxygen. A cask of Fino is considered to be Amontillado if the layer of flor fails to develop effectively, or is intentionally killed-off by additional fortification, or it is allowed to die off through non-replenishment.

 

Without the layer of flor, Amontillado must be fortified to approximately 17.5% alcohol so that it does not oxidise too quickly. After the additional fortification, Amontillado oxidises more slowly, exposed to oxygen through the slightly porous American oak casks. It achieves a darker colour and richer flavour than a Fino - naturally a dry style Sherry; they are sometimes made light to medium sweet.
An Amontillado Sherry can be produced in several different manners. A ‘Fino-Amontillado’ is a wine that has begun the transformation from a Fino to an Amontillado, but has not been aged long enough to complete the process; the result a ‘medium sherry’ is an Amontillado that has been slightly sweetened. Then there is an ‘Amontillado del Puerto’ Sherry, which is an Amontillado specifically made in El Puerto de Santa María.
Due to its oxidative aging and preparation, Amontillado is more stable than Fino and may be stored for a few years before opening. After opening, it can be kept for up to two-three weeks, if re-corked and stored in the fridge.
Amontillado Sherry is usually best served slightly chilled, and may be served either as an apéritif, or as an accompaniment to food such as chicken, veal, pork or rabbit with mushrooms. Classically it was served with a fine, or thin, soup, like a beef consommé.