Bring a large pot of water to a boil. While water is heating up, clean and trim green beans. Fill a large bowl with ice water and set aside.
Add green beans to boiling water and cook for one minute. Promptly remove green beans and add them to your bowl of ice water to stop them from cooking any more.* Strain beans and set aside while you make the vinaigrette.
In a large bowl, whisk together the remainder of the ingredients.
Add green beans to the vinaigrette and toss to combine. Serve immediately if short on time, or marinate in the fridge for 30 minutes to an hour before serving.** Top with crumbled feta and enjoy!
Notes
*This process of scalding the green beans and quickly moving to an ice bath is called blanching. It helps extract the bright green color, and keeps your green beans nice and crisp after being tossed in the vinaigrette.**I prefer to let them marinate for a while- the flavor develops and the shallots mellow out a bit, although it is delicious right away!