1. Cut tofu into 1/2-inch thick slices. Place slices on a double layer of paper towels. Place paper towels over top and press gently, to blot. Transfer tofu to chopping board and cut into cubes. Transfer to a small bowl.
2. In a medium bowl, combine soy sauce, rice wine, ginger, sugar, garlic and 2 teaspoons of the cornstarch. Pour half of the marinade over tofu. Add beef to remaining marinade. Stir both tofu and beef mixtures gently, to coat with marinade. Cover and chill for 2 hours, tossing occasionally.
3. Drain tofu and beef, reserving marinades. Combine marinades with chicken broth and remaining 1 teaspoon cornstarch; set aside.
4. Heat 1 tablespoon oil in a large nonstick skillet. Add beef to pan. Stir-fry 2 to 3 minutes or until beef is desired doneness. Remove to bowl. Add remaining oil and broccoli to skillet; stir-fry 2 minutes. Add tofu; gently stir-fry 2 mintues more. Return beef to pan; stir sauce; add to skillet. Cook, stirring gently, until mixture boils; cook 1 minute more. Serve immediately with brown rice.