In a large nonstick saucepan, heat 1/4 cup of the chicken broth over medium-high heat until it simmers. Add the celery, onions and bell pepper and cook until the vegetables are tender-crisp, about 4 to 5 minutes. Reduce heat to low, allowing the mixture to cool slightly.
In a medium bowl, add the turkey or chicken cubes and flour. Toss gently until the flour coats the meat. Add to the vegetables and broth, cooking over low heat for about 5 minutes. Increase heat to medium high and slowly add the remaining broth, wine, parsley, rosemary and black pepper. Cook and stir until the sauce thickens slightly. To serve, spoon 1/4 of the casserole over each piece of toast.