First You need to get to the swamp and get some Turnip seeds before you can actually make sausages. You have to make a "spice rack" which needs 2 Turnips to craft. The rack will upgrade your Cauldren to rank 2 and let you actually make sausages.

I believe the recipie for sausages will unlock once you pick up some Drauger entrals but you will need that space rack before you can use it. As TheBoot mentioned above you'll also need some Thistle.

Good hunting