You have your harvested fruit and vegetables on the kitchen counter or island. 
You have been using them at your leisure when you discover the first annoying fruit fly of the season.

How to rid yourself from the army that is about to come. Easy!! First, check to make sure none of your fruit or vegetables have over-ripen and became soft and/or mushy. Discard any that you find. Then, fill any small container, small canning jar, empty pudding container or any small bowl, with 1/2 cup of cider vinagar and just a few drops of dish soap. ( I used the blue one )

The flies will be attracted to the smell and fly in and die. You would be amazed how quickly it works. Try it out for yourself.

Some people like to place plastic wrap over the top and poke a few holes in the top. From my experience, this is not really needed unless you have small animals or children that could spill the open container.

Once the container has been on the counter for a few days, rinse and refill as stated above until no more fruit flies are seen.