Could you please explain why the melachah of kore’ah would not apply to opening the flap of the tea bag, which is actually attached (albeit very flimsily) to the body of the bag. Wouldn’t separating the flap from the bag be kore’ah? I am referring to opening the tea bag the regular way.
Magen Avraham (340:18) writes that if pages were stuck together by wax, it is permitted to separate them, because they were not stuck together in a permanent way. He adds that this is all the more true in the case in point, when the pages were stuck together without intention. This ruling is quoted by a number of authorities (see Shluchan Aruch Harav 340:17; Mishnah Berurah 340:45). Chayei Adam (29:1) adds that the first reason is sufficient: the fact that the pages were not stuck together in a permanent way, but were rather stuck with the intention of splitting them apart, there is no question of kore’ah involved. This is ruled with regard to opening bags by Rav S. Z. Auerbach (Shemiras Shabbos Kehilchasah chap. 9, note 19), and is all the more true with regard to tea bags, whose connection is very flimsy, and can hardly be called a connection at all.