I have heard that Rav Nachum Rabinovitch, shlit"a, (who, IMSMC, is strict regarding using tea bags/cold essence to make tea on Shabbos, even in a kli sheni [lit: second utensil]) is lenient with regard to Israel's Wissotsky teas because the tea leaves have purportedly already undergone a process of bisul (cooking) and ein bishul achar bishul (There is no halachic problem of cooking pre-cooked items on Shabbos. Lit: There is no cooking after cooking.) I was curious to confirm if this is indeed the case that Wissotsky has a unique processing technique distinguishing it halachically from other brands of tea. How and why do they process their teas differently?
From their website, I see no indication or mention of any bishul process distinct from other tea-makers. Does Rav Rabinovitch perhaps side with the Ra’avya (ch. 197, p. 256) against the Yere'im (ch. 274, 134b; see Shulchan Arukh 318:5) and rules that ein bishul achar afiyah (There is no cooking after baking)? The sense from their site is that no significant heat is employed to justify such an interpretation either, even assuming that leniency. Do they indeed employ a greater level of heat than other tea manufacturers? Can anyone confirm/deny this ruling and reasoning of Rav Rabinovitch?
(Related: Source for heter for making tea on Shabbos)