Pedro Ximenez, or PX in its shortened form, is the name of a white Spanish wine grape variety grown in several Spanish wine regions, but most notably in the Denominacion de Origen (DO) of Montilla-Moriles.
In Montilla-Moriles it is used to produce a varietal wine, an intensely sweet, dark, dessert sherry. It is made by drying the grapes under the hot sun, concentrating the sweetness (similar to straw wine production), which are then used to create a thick, black liquid with a strong taste of raisins and molasses that is fortified and aged in solera.
Recent years have seen producers in South America experiment (somewhat succesfully!) with the Pedro Ximenez grape variety, favouring the drier side of the wines capabilities, making medium bodied wines with characteristic tropical fruit flavours.