I found an item on timeless isle sitting on the ground west of the treasure chest cave. I clicked and looted an item that started a quest that taught me the noodle and grand noodle cart recipes. Not sure of the other ones you mentioned though.
They actually hotfixed it Monday, it's already good to go. I went out on my priest and got all 6 with 9 keys, so the droprate is pretty decent.
What time Monday cause I had two guild mates out there almost all day doing those chests ...one even looted and opened up over 30 chests and no recipes what so ever....I think they are not in game yet really...cause of those doing for hours and nothing but cooking mats coming up...I even went out there with them and looted 6 chests and not 1 recipe at all.
PSA: You can buy 5 pieces of food from the cart, then sell them back, buy 5 more, etc., etc. Then buy them back from a vendor mount or repair bot. Really extends the life of the noodle cart, and lowers the cost of food. Don't get too used to it, I'm expecting a hot fix to make this no longer work, either by making them have no sell value, or some other means.