Food in any shape or form that can feel pain, have the ability to solve problems and think, and is equipped with vocal cords which allow it to beg for mercy as it is being eaten. Sapient food in the shape of tiny bionts is especially popular, since they constantly try to run away. Banned throughout much of the terragen sphere except for some barbarous regions.
There are various ways of classifying sapient food - for example sapient food that dosn't want to be eaten, and food that does. The latter generally has pleasure receptors instead of pain, perverse psychological (willing victim inclination) and/or memetic engineering, and so on. Also, in cases of willing developed vertebrate-type sapient food, the blood vessels would automatically close to prevent shock from blood loss setting in when being eaten, and so on.
Very often humanoid sapient food is tiny; there is generally less squeamishness about eating tiny humanoids than about eating those the same size as oneself.
Growing or nanofacturing and distributing even tiny sapient bionts that want to be eaten is illegal in much of the Civilized Galaxy. Even so, there are always those regions, especially some more barbaric non-aligned worlds, and some antinomian NoCoZo polities and free zones, where one can go to find sapient food, whether sentient fruits or even fully developed miniature or larger bionts. What is legal and what not also varies from polity to polity, even within a single sephirotic empire, although all strongly aligned worlds and polities have very similar legal/sentient rights. And obviously, sapient food is not possible in angelnetted worlds and polities that recognize sentient rights
Very often, sapient food is among the "forbidden delights" that some Free Zones and antinomian polities use to tempt perverse visitors (Sensationalist Tourism).