Prepare rice according to package directions. About 15 minutes before rice is done, melt margarine in 12-inch skillet over moderate heat. Sauté onion for 5 minutes or until clear. Move onion to one side of skillet; add chicken and sauté for 5 to 8 minutes or until chicken is no longer pink. Stir in flour, tarragon, basil, thyme, salt, and rosemary. Add chicken broth and tomato paste stirring constantly for 3 minutes or until sauce has thickened. Pour mixture over brown rice and serve.