Place the barley in a medium pot; add water and bring to a boil. Reduce heat to simmer, cover and cook for 40 minutes or until all the water is absorbed.

Refrigerate for at least 1 hour. Heat the oil in a large skillet or a wok. Add scallions, celery, carrots, and daikon; saute'. When vegetables are tender, add barley. Toss them all together and heat. Sprinkle with soy sauce, shaking it across the pan to cover the barley mixture. Toss to mix.