Heat the oven to 350 F. Lightly coat a baking dish with cooking spray.
Trim the ends off the eggplant and cut in half lengthwise. Using a spoon, scoop out the pulp, leaving a shell 1/4-inch thick. Place the shells (cut-side up) in the baking dish and add the water to the bottom of the dish. Chop the eggplant pulp into cubes. Set aside.
In a large, nonstick frying pan, heat the olive oil over medium-high heat. Add the chicken strips and saute until the chicken is lightly browned and no longer pink, about 5 minutes. Add the diced eggplant, onion, peppers, tomatoes and reserved tomato juice, celery, and mushrooms to the chicken. Reduce heat and simmer until the vegetables are tender, about 10 minutes. Stir in the bread crumbs and black pepper. Scoop half of the mixture into each eggplant shell.
Cover with aluminum foil and bake until the eggplant is softened and the stuffing is warmed through, about 15 minutes. Transfer the eggplant to warmed individual plates and serve immediately.