"제가 먹었던 피자는 컸어요."
Translation:The pizza I had eaten was big.
"The pizza I ate was big". Why is this wrong? Sorry if the answer seems obvious, but I am having difficulty with the translations for the Korean sentences and would appreciate any further explanations to clarify this.
The pizza I ate would be better. If you say: had eaten, you would generally add a following action. E.g. I was tired once I had eaten the pizza
Oh boy, hard to explain. So, ~던 is also used for describing things in the past, but it's a very subtle nuance of having a memory of something. Just 먹은 has no emotional connection to the pizza, so using 먹었던 makes it seem like it was a memorable moment.
I agree with @wintertriangles about the nuance of remembering, having a flashback.
You can read more about it in (too much) detail on the howtostudykorean website.
In my KIIP class, we also saw this example to understand the difference between the present and past form of this pattern:
그 책은 제가 읽던 책이에요 --> you haven't finished reading yet, you are in the process of reading the book.
그 책은 제가 읽었던 책이에요 --> you finished reading that book.
Hard to understand but read this: