Step #1 In a kettle of boiling salted water boil the haricots verts for 4 to 6 mins, or until they are crisp-tender, drain them, & plunge them into a bowl of ice & cold water to stop the cooking.
Step #2 Drain the beans again & pat them dry.
Step #3 The beans may be prepared up to this point 1 day in advance & kept wrapped in dampened paper towels in a plastic bag & chilled.
Step #4 Just before serving, in a large skillet melt the butter over moderately high heat & in it toss the haricots verts until they are heated through.
Step #5 Spice up the haricots verts with salt & pepper.