Sources

Spain

Virtual Cervantes Library at http://cervantesvirtual.com and it contains many fulltext books from late-period Spain.

“Arte Cisoria” (1423 carving/serving manual)
“Manual de Mugeres” (late 15th century household manual w/ recipes for foods, perfumes, cosmetics & medicines)
“Obra de Agricultura” (agricultural/animal husbandry manual, c. 1513)

pieces of German cookery texts from 1350-1800 appear at: http://www.uni-giessen.de/~g909/kobu.htm
Das Kuchbuch der Sabrina Welserin text is translated at: http://www.best.com/~ddfr/Medieval/Cookbooks/Sabrina_Welserin.html

Roman era

De Re Coquinaria by Apicus or Cooking and Dining in Ancient Rome on Project Gutenberg

Du fait de cuisine is at: http://www.best.com/~ddfr/Medieval/Cookbooks/Du_Fait_de_Cuisine/du_fait_de_c_contents.html
Le Ménagier de Paris (a medieval manuscript dated to circa 1393), edited by Jérome Pichon in 1846 for La Société Des Bibliophiles François in French.
Le MÈnagier De Paris (Janet Hison) in English. Translated from the French edition of Jerome Pichon published in 1846. Footnotes marked JP are by him; those marked JH are by Janet Hinson, the translator; those marked DDF and EGC are by David Friedman and Elizabeth Cook, respectively.

Cariadoc’s Miscellany links to translated sources is: http://www.best.com/~ddfr/Medieval/Medieval.html
Serve it Forth!!, a hardcopy medieval/renaissance cookery newsletter about pre-17th century cooking, culinary sources, culinary history, ingredients, food, and foodways. It contains book reviews, recipes (both original and redacted), feast plans, tips on kitchen management and the preparation of feasts, anecdotes, and articles and research about all of the above.