In a small bowl whisk together the vinegar, the oil, and salt and pepper to taste. In a large saucepan of boiling salted water cook the green beans for 4 minutes, add the snow peas, and cook the vegetables for 30 seconds. Drain the vegetables, transfer them to a bowl of ice and cold water to stop the cooking, and drain them. Pat the vegetables dry between several thicknesses of paper towels and in a bowl toss them with the sunflower seeds and the dressing.
