1 tablespooncornstarch, mixed with equal parts water
In a large bowl, combine beef tips and soy sauce. Set aside for 15 minutes.
Heat oil in a wok or large heavy skillet over medium heat. Saute garlic for about 30 seconds or until fragrant. Increase heat to high. Add beef and marinade, then stir-fry until cooked through, about 10 minutes. Stir in water and sugar. Add broccoli, and cook stirring until soft, about 10 minutes. Pour in the cornstarch mixture, and cook until sauce is thickened, about 5 minutes.