Cover and cook for 5 minutes over low heat or until vegetables are crisp-tender. Add to chicken mixture. Cook until the mixture thickens and bubbles. Stir the mixture constantly while it is cooking. Serve over hot cooked rice.
Open tuna can and drain tuna.
Put tuna in small bowl. Wash and chop celery on cutting board. Add celery and mayonnaise to tuna in bowl. Place 4 slices bread on cutting board. Spread tuna over bread and put another slice of bread on top.