Its is a common SCA myth that tomatoes were not available in Europe in the SCA period (pre-seventeenth century).
In fact, as with many New World (read North and South Americas) foods (like chocolate), it was in fact known, and utilised, if in different ways to the modern palate. If anything, its rarity value made it more of an expensive novelty to start with.
They were known as "Golden Apples", and were for example eaten as follows:
"The golden apple one eats in the same way as the eggplant with pepper, salt and oil, but it gives little and evil nutrition." (Source: "Herbario nuovo", Roma, 1585, dall'introduzione di Piero Camporesi a "La scienza in cucina e l'arte del mangiare bene" di Pellegrino Artusi)
For an excellent discussion on tomatoes and their use in the SCA period, read this excellent article available at Stefan's Florilegium: http://www.florilegium.org/files/FOOD-VEGETABLES/16C-Tomato-art.html