Quote Originally Posted by Throbert McGee View Post
"Она добавила горсточку сахару", "She added a small handful of sugar"? Or would сахара be preferred there?

And I'm pretty sure that "я выпил чая" and "я выпил чаю" are both okay (with a partitive meaning that's different from "я выпил чай").
There's no need to use partitive genitive there, because the word горсточку already suggest that you use a part of something and not the whole thing.
However, if you say just --- она добавила сахару --- it would be just fine.

What about чай thing I'd personally say я выпил чай or я выпил чаю, the second is much more preferable, at least for me.

In substance, partitive genetive is quite an interesting phenomenon. For example, here are the two sentences which mean absolutely different thing:

Он вылил (poured out) чай из стакана and он вылил (poured out) чаю из стакана.

I think you Throbert can understand both of them properly