LORELAI: Huh, Kosher bacon.
SOOKIE: Beef, not pork.
LORELAI: I am so Jewish.
Beef bacon is made from beef belly, so that it’s streaked with fat like pork bacon, and then cured, dried, smoked, and sliced in exactly the same way. It’s leaner than pork bacon, though. It’s recently become popular because it’s halal and kosher – there’s a big market for it in the Middle East – but it’s not a new product. Bacon was made from beef and mutton as well as pork hundreds of years ago.
“I am so Jewish” is presumably a meta-comment from the writer, Amy Sherman-Palladino.