Haricot vert and regular green beans, distinguished
In culinary lingo, however, when a recipe calls for haricot vert, it refers to thin green beans sometimes labeled in the market as “French beans”. They are about a quarter of an inch thick, they are more tender than regular green beans and the strings on both sides are almost non-existent. They are also less fibrous and more crisp.
Considering all those characteristics, does that simply mean that haricot vert is just very young green beans? Not exactly.
…haricots verts tend to be skinnier than traditional green beans, and are also more expensive. They’re actually bred that way: not only are they thinner, they’re also more tender and flavorful than comparably sized traditional green beans. They’re also younger than traditional green beans; if you were to pick regular old green beans at the same age at which haricots verts are harvested, they’d be missing a lot of that “beany” flavor.
The Daily Meal
There are several varieties of green beans but haricot vertrefers to a variety with specific characteristics, and grown and harvested under specific conditions.
For food writers and recipe developers, the distinction can be even more significant. No one wants to call a dish “haricot vert salad”, for instance, when the accompanying photo in the recipe obviously shows that the beans used cannot possibly be considered as thin green beans. “Haricot vert salad” might sound cool and sophisticated but you will get laughed at for your ignorance and pretentiousness by any person who can tell the difference between haricot vert and regular green beans.
In practical cooking, however, I find that one can be substituted for the other.
How is haricot vert prepared for cooking? Rinse and cook. Like I mentioned earlier, there is hardly any string along the sides.
How long should haricot vert be cooked?

Seven to ten minutes in the steamer basket over briskly boiling water. Just spread them well so that each piece gets hit by the steam. They cook evenly that way. And don’t overcook. Cook them longer and you will lose the crispness that makes haricots verts so delightful.