Paco's got it.
"Did you like the dinner last night?" implies that a special occasion
had occurred. Perhaps the dinner was an occasion to celebrate
something. One almost wants to add more to the sentence.
"Did you like the dinner given to the employees to celebrate our record
profits this quarter?" 'dinner' is countable here. "Our
club used to arrange two dinners a month for the members. The
dinners were always accompanied by special lectures."
"Did you like dinner last night?" asks mostly about the food, although,
depending on context, it may refer also to other elements associated
with dinner, such as the conversation. 'dinner' here is a
non-countable noun.
CJ