These may seem trivial, but I cannot tell you how many times I have been jerked out of a fantasy world by food references that seem wrong. If you don't remember that potatoes and tomatoes are New World foods and would not have existed in European-based fantasy worlds, I am annoyed. Turnips were the roots used before potatoes, and let me tell you, people were glad to get potatoes, tastier and more nutritious (despite what stupid modern nutritionists tell you about the evils of potatoes). Corn, also was a New World food. Before that, the word "corn" referred to any grain. The Indian word "maize" is the word that specifically refers to the yellow grass vegetable/grain we eat in America now. So think about these questions as you write:
What are the ethnic roots of this food?
What roots were grown here originally?
What plants have been imported and from where?
What foods are most nutritious?
What foods are most coveted and most expensive? Breast meat of chicken or the eyes of the fish?
What food do the poor eat? Offal, or potatoes or corn?
Are smelly foods desirable?
How do they eat soup?
What utensils are in use commonly?
What are the table manners?
What rituals surround food?
Who eats with you?
Are there gods to thank for the food?
What prayers might be said over the food?
What do people do to ensure a plentiful harvest?
Is the food form the land or the sea?
How much trade is involved in each meal?