I noticed some of the new foods are for sale and can be made on the normal cooking spits. Mudcrab legs were added to the spits, which are made by mudcrab chitin and butter. But I would guess most of the new food, like the two you mentioned, would need to be cooked in the new ovens.
I haven't seen any outside the player house with the right upgrades, but I haven't played much with the DLC installed though.