1. Mix the rice, onion, green pepper, celery and salt in a small bowl. Add the water; stir to blend. 2. Divide the whole chicken breasts; you will need 4 pieces. Tear 4 pieces of foil about 15 inches long. Divide the rice mixture into four portions, one portion to each foil piece. Place the foil onto a cookie sheet with edges of foil turned up so liquid does not run out. Place one piece of chicken on top of each portion of rice mixture. 3. Blend the soup and milk; spoon equally over the chicken. 4. Thaw the mixed vegetables just enough to separate. Arrange the vegetables around the chicken. Bring long ends of foil up and fold carefully. Fold the two sides up and seal so juice will not run out. Place packs on a cookie sheet in a preheated 375-degree oven. Bake for 1 hour. Fold back foil and serve in the foil if desired.