Preheat oven to 400 degrees Fahrenheit.
Mix the broth, lemon juice, olive oil, onion powder, garlic powder, tarragon and celery in a glass 9″x13″ baking pan. Add the chicken breast in a single layer.
Bake uncovered for 20 to 30 minutes or until chicken is cooked through and the liquid is bubbling. Remove from oven and cool in liquid. Slice each chicken breast on the diagonal and transfer chicken and liquid to a sealed plastic container and refrigerate until ready to assemble sandwiches.
To assemble sandwiches: Spread bottom half of roll with Dijon mustard. Layer lettuce, tomato slices, red onion slices and chicken and top half of roll.
If you’re watching your carbohydrate intake, this chicken is also delicious on a green salad, and even better garnished with goat cheese.