Why use passé composé instead of l'imparfait when referring to restaurant?

Question

Hi,

I'm wondering why we would say 'on a dégusté des spécialités lyonnaises' rather than 'on dégustait des spécialités lyonnaises'. I thought that we would use the imperfect in this case as it happened over an extended period of time?

Accepted Answer

The text just states that they went to a Restaurant to enjoy Lyonnese specialties. I understood this to have been a singular event in the past and therefore a prime candidate for the passé composé.
You'd use the imparfait if you wanted to say, e.g., that they were always eating at that restaurant during their vacation.

Answer

The period of time is dinner, and is thus fixed, or over.