In a small bowl, whisk salad dressing, lemon juice, Mrs. Dash, salt and pepper. Trim asparagus ends, but leave the rest whole. Bring pot of water to boil. Add asparagus and cook 7-10 minutes or until al dente.
Drain asparagus, then add chicken, tomatoes, asparagus, and dressing mixture to pot and cook over medium heat until mixture is warmed through and chicken is no longer pink, about 5-7 minutes. To serve, line each plate with 2 cups salad greens. Add chicken and asparagus mixture over greens.