Bring 2 inches water to a boil in a large skillet. Salt water once it comes to a boil. Blanch haricots verts in boiling water 2 minutes, drain and cool. Pat beans dry on paper towels.
Dry skillet as well and return to heat. Heat pan over high flame and add oil to coat the bottom of pan. Add beans to hot oil and stir fry using tongs to move and toss the beans until they are charred and very hot, 3 to 4 minutes. Sprinkle beans with sesame seeds and cook 30 seconds more, to both toast the seeds and distribute them. Pile fried beans onto a serving plate and sprinkle with salt, to your taste.