I’m not really confident about what qualifies as “common food” or “typical western diet”, nor the accuracy of the following sources, but I feel like if someone’s going to answer OP, they should have something to back it up.
There are two schools of thoughts regarding the home of onion cultivation, and both look at the period 5,500 years ago in Asia. Some scientists believe that onion was first domesticated in central Asia and others in Middle East by Babylonian culture in Iran and West Pakistan
The extraction of sugar cane juice from the sugarcane plant, and the subsequent domestication of the plant in tropical India and Southeast Asia sometime around 4,000 BC.
Examining the origins of the dry bean takes us back to South America. These, serving as a dietary cornerstone, were initially cultivated over 7,000 years ago in the southern regions of Mexico and Peru.
People have been farming corn, or maize, for thousands of years. Native civilizations in present-day Mexico first domesticated corn around 10,000 years ago.
Around here (Sweden) I would bet a bit that any fish from the Baltic Sea is both common and super old member of the diet for the population around the water. Salmon is also a great contender being found in the rivers as well.
Any of the easily hunted animals that are still around, don’t know if it’s “common” if it’s seen as a delicacy outside of hunting families though
I’m not really confident about what qualifies as “common food” or “typical western diet”, nor the accuracy of the following sources, but I feel like if someone’s going to answer OP, they should have something to back it up.
Onions - 5,500 years ago
http://www.vegetablefacts.net/vegetable-history/history-of-onions/
Sugar - 6,000 years ago
https://en.wikipedia.org/wiki/History_of_sugar
Beans - 7,000 years ago
https://cablevey.com/history-of-dried-beans-how-it-all-started/
Corn - 10,000 years ago
https://cropcareequipment.com/blog/corn-farming-history/
Potatoes - 13,000 years ago
https://spudsmart.com/domestication-of-the-potato/
Around here (Sweden) I would bet a bit that any fish from the Baltic Sea is both common and super old member of the diet for the population around the water. Salmon is also a great contender being found in the rivers as well.
Any of the easily hunted animals that are still around, don’t know if it’s “common” if it’s seen as a delicacy outside of hunting families though
I think fish is a likely winner - it’s something we likely hunted and gathered and continue to consume in generally the same format over the years.