The agave heart, or piña, is the swollen central stem of the maguey plant, trimmed of its spiny leaves to leave a dense pineapple-shaped core that is pit-roasted until the raw sap turns to sweet amber flesh. Best known as the starting point of mezcal and tequila, the cooked heart is also eaten in its own right across rural Mexico — chewed for its molasses-sweet, smoky, fibrous strands as a wild sweet and a caramel-tasting vegetable long before the plant ever reaches a still.