Heat beef broth in saucepan with lid, when boiling, add brown rice and simmer, covered, for 40 minutes.
Meantime, place the ground beef in a skillet over medium-high heat. Cook, while stirring to crumble, until almost cooked through. Drain the grease, and reduce heat to medium. Stir in the celery, green onions, and tomato. Cook until the celery is tender, and the beef is browned.
Stir the rice into the vegetables and beef, and season with salt and cayenne pepper.