Many of the well known European food items (such as potatoes in Ireland or Tomatoes in Italy) came from the New World. What were common food items in Europe before the Americas were discovered?

This is probably a broader question than it sounds like. The exact type of food depended on the region, so all the foods I'm going to mention were not accessible to everyone at all times, but being the birthplace of Agriculture and pastoral herding, the entire Old World of Europe, Asia, and Africa had a cornucoppia of delicious foods to call its own before the Columbian Exchange brought over the ingredients we associate with it today.

Grains like wheat, barley, rye, and oats were probably the most significant crop humans domesticated, enbling agricultural urban civilizations and dominating kitchens before and after contact with the New World. These staple cereals could be most simply made into porridges, but often more popular than gruel was the grinding of grain into flour and making it into bread. Flatbreads, leavened breads, crusty or chewy breads, salty or sweet... the art of baking had long been mastered before Europeans found the Americas. Still porridge was not considered too poor a dinner. It could be flavored with all sorts of Old World herbs and spices such as coriander, cumin, oregeno, mustard, thyme, and sesame just name only a few, or sweetened with honey or fruits like apples, cherries, peaches, pears, pommegranates, and most often figs or dates. Rice was grown in the east Other crops grown and domesticated for the dinner table were onions, garlic, eggplant, lettuces, lentils, and chickpeas. Greens, in the forms of salads or cooked down, often gathered in the wild, were immensely popular, and known for thosuands of years to provide health benefits.

Everywhere and anywhere people lived by a river or coast, fish was of course a major staple. Fermented fish, or fish sauce, was especially popular since prehistoric times as a flavoring and condiment. Meat, however, was rarely enjoyed except for by the very wealthy. Even for the herders who literally raised flocks of potential meat, animals were far too valuable a source of wealth alive to kill and eat regularly. Still, nearly all the major farm animals were domesticated in Asia and the Near East. Goats, sheep, pigs, horses, cows, and camels were all the potential choices of meat for those who could afford it. And the common poor, for what it was worth, probably got to eat meat occasionally when necessity called for slaughter, or when provided at public festivals across times and cultures.

But if not animal meat, then animal products like milk, butter, buttermilk, yogurt, and of course CHEESE, were featured all over the Old World diet. Not only that, few would probably argue that the very best cured meats and fine cheeses today come from traditions founded in Europe. Spanish jamon, Prosciutto di parma, Greek barrel feta, and parmesan reggiano come to mind first, but are just the beginning.

Beer and wine have been enjoyed, probably a little too much, since ancient times, and finally, to round out this incomplete list of the variety of foods native to Europe, Asia, and Africa, my personal favorite, olive oil, was used as a cooking fat or dressing, though many cultures did use butter, animal fats, or even sesame oil more frequently.

The Columbian Exchange massively changed Old World Cuisine, but it didn't reinvent it from the ground up. It infected the thriving culture of food and dining that was already there. Even though WE might think about tomatoes when we think of Italy, or about Swiss Chocolate or Asian Chilis, that oversimplification neglects the wide array or foods available in different parts of the Old World before contact with the Americas.