Heat oil in deep, heavy skillet or wok over medium-high heat; add garlic and cook until a bit of garlic sizzles at once. Toss well. Add beef and toss until it changes color. Add broccoli florets and toss for about 1 min., until they turn shiny and bright green. Add oyster sauce, fish sauce, sugar, pepper, and water and cook 3-4 min., tossing often, until broccoli is tender and beef is cooked. Transfer to small serving platter and serve hot or warm.