Oh, that’s a hard one. It really depends on what you want to learn. While I can recommend each and every of the smaller Teubner books, they can be quite pricey since the new edition is not as good as the older ones (on the upper shelve). However, the big Teubner “Deutsche Küche” and "Küchenpraxis (lowest shelve) are wonderful too, and you can get them relatively inexpensive on eBay. If I had to choose just one, I’d go with “Küchenpraxis” since it’s the most comprehensive for Wares, Produce, Procedures and an assortment of recipes.