I am always looking for a diffrent way to cook my beloved green beans. My family will actually eat them if I start with fresh green beans. the directions are for cold green beans but I am sure you could serve them warm with the vinaigrette.
In a large saucepan bring 1 inch water to boiling. Place green beans on a steamer rack and set the rack in the pan. Cover and steam 7 minutes or until green beans are tender. Immediately transfer green beans to a bowl of ice water then drain.
Meanwhile, for the dressing, in a small bowl whisk together the lemon juice, zest, dill, oil and mustard.
Place green beans in a large serving bowl. Add dressing, toss lightly to coat.