Like most continental European countries, every city and town in Holland has a general open-air market that is held at least once a week.
In Utrecht, the Vredenburg market is held on Wednesdays, Fridays, and Saturdays. My boyfriend goes there on Saturdays to buy fresh eggs.
I visited the market yesterday and noticed that there weren’t many fresh fruit and vegetable vendors, but there were stalls selling Dutch cheese, flowers, fresh fish (which you could get fried in front of you for lunch), nuts and snacks, and clothes.
There are also a number of specialized markets throughout The Netherlands, such as the traditional cheese market in Alkmaar, the bloemenmarkt (flower market) in Amsterdam, and various flea markets, second hand book markets, and cloth markets.