Bring a large saucepan of water to a boil. Add rice and cook until tender, about 50 minutes. Drain; transfer rice to a large mixing bowl.
In the meantime, bring a large saucepan of water to a boil. Add snow peas or green beans and boil until bright green and just tender, about 1 minute. With a slotted spoon, scoop out beans and drain in a colander. Return water to a boil and add orzo. Cook until tender, about 10 minutes, drain well. Add green beans, orzo, peppers and onion to rice in bowl and mix gently.
To make the dressing, place the vinegar, oil, ginger, parsley, and mustard in a food processor or blender, process until well blended. Pour dressing over rice mixture and toss to coat. Serve at room temperature.