Preheat oven to 375 degrees F (190 degrees C). Lightly grease a baking dish.
Place the chicken breasts in the prepared dish. Mix the tomato sauce, water and taco seasoning in a small bowl; pour sauce over the chicken.
Bake in preheated oven until chicken is no longer pink in the center, about 30 minutes.
Divide spinach between two plates. Place the chicken breasts on the spinach beds and spoon half the black beans over each piece. Divide sour cream, shredded cheese and salsa to top each salad.
