We usually go over them at the end of class, with enough time for questions and explanations. Sometimes I have my students grade each other's quizzes in class in order to facilitate explanation of errors. My favorite method of correcting compositions is by simply circling the mistake. Then the students rewrite the compositions, trying to correct the mistakes the best they can. In my experience, students are engaged in language learning a lot more than by simply reading compositions with explained errors.
Oral evaluations are always stressful for the students.
To minimize the nervousness and panic I usually have the students talk to each other rather than interviewing them myself.