When writing historical fiction or fantasy, the question of food either seems daunting or is completely overlooked.  With the Historical Food Timeline, you can get an approximate idea of when a given food was introduced.  Though it does slant to Western Europe and America, it is still a good touchstone for getting a feel for if it is all right to give your character a yogurt.

At the same site, they have the Historic Food Prices and a survey of meal times. Don’t make the mistake in your fantasy of assuming that your local dining habits are universal.