Fill a bowl with ice water. Cook the green beans in salted boiling water until tender but still bright green, about 5 minutes, then drain and chill in the ice water to stop the cooking. Remove from the ice water and pat dry.
In a large bowl, whisk together the hazelnut oil, vinegar and honey, and season to taste with salt and pepper. Add the green beans to the bowl with the dressing and toss to coat, adding more salt and pepper if needed. Transfer to a serving bowl or platter and top with the toasted nuts and lemon zest.