Why is conditioned taste aversion an example of classical conditioning (rather than operant)? The internet seems to be in complete agreement that conditioned taste aversion is an example of classical (Pavlovian) conditioning. My (admittedly limited) understanding of classical conditioning is that it's a process in which two stimuli are paired in such a way that the response to one of the stimuli changes. I'm having trouble spotting what those stimuli are in this case. This seems more like operant conditioning, in which unpleasant consequences (the symptoms) mold behavior by causing us to associate the taste of that food with those symptoms.

Am I misunderstanding operant/classical conditioning? Am I overcomplicating things?
The conditioning of aversion to taste is part of learning studies in which there is an association between food and flavors with positive reactions such as food preferences or satiety and negative reactions such as lack of appetite, gastric discomfort, etc.

For example, it has been shown that patients with gastric discomfort acquire aversion to food, or patients (who have received prior chemotherapy) are averse to food when going to receive new sessions (chemotherapy usually causes nausea).

It is usually considered a classic conditioning learning. For example, foods that are neutral or independent stimuli before learning, produce conditioned responses (after the learning process), for example nausea, so foods are conditioned stimuli that produce conditioned responses (conditioned responses never they are exactly the same as the responses of the absolute stimulus).

Not only stimuli (foods or flavors) can produce a conditioned response but also events (such as being close to another session of chemotherapy).

Stimuli > CR

Events > CR

This is why in general it is considered classic conditioning, since the person (or animal) can not control the consequences with their behavior as it occurs in instrumental learning.

If for example you are thinking about the learning process of a person who tastes a food (with control over being able to try that food for the first time) and the food does not like it, in that case it is evidently instrumental learning. Of course, in relation to food learning, not everything is classical conditioning. The fundamental thing is to handle the concepts of analysis of the types of conditioning.

It is essential to read the section on Learning to taste aversion in the book by Michael Domjan. Principles of learning and behavior. Pages 72 to 74 in the 3 edition. It is interesting to review the studies indicated in this section.