shabbat - Source for heter for making tea on Shabbos

There appear to be a few issues with brewing tea on Shabbos, some of which have already been discussed here:

1. Kli Sheini and Kli Shlishi (see here and here)


2. Kalei Bishul


3. A heter from Rav Moshe

I'm not sure how all those come together to form the opinion (for which I do not know the source) that brewing tea on Shabbos is allowed. Could someone explain to me where the heter comes from?

Answer

Rabbi Soloveichik -- tea is like the spices discussed in the Mishna in Shabbos, a kli sheni doesn't cook them. Therefore, pour the hot water into your cup, then insert tea bag. Kli sheni, you're fine.

Rabbi Moshe Feinstein -- the Mishnah only discusses kli sheni; kli shlishi doesn't cook. So pour water from pot into cup 1, then cup 2, then insert tea bag.

Is that what you were looking for?