In a small saucepan, combine cornstarch and sugar. Stir in the broth, soy sauce and vinegar until smooth. Bring to a boil; cook and stir for 2 minutes or until thickened. Set aside and keep warm., In a large bowl, whisk flour and eggs until smooth. Stir in bean sprouts, crab, onions, garlic powder and pepper. In a large skillet, heat oil. Drop crab mixture by 1/3 cupfuls into oil. Cook until for 2 minutes on each side or until golden brown. Serve with sauce.