In a small bowl combine the raisins and ¼ cup warm water and set aside to soak.In a medium bowl toss together the carrots, walnuts, green onion, celery and bell pepper, vinegar, oil and mustard. You'll want to stir and toss well so everything is well combined. Drain the raisins, reserving 1 tablespoon of the water. Add the raisins and reserved water to the carrot mixture. Toss again. Taste and adjust the seasoning adding salt, pepper and/or additional vinegar or mustard to taste. Refrigerate until ready to serve.