In a small bowl, using the bottom of a glass or jar, crush the peppercorns into a coarse pulp. Stir in the cilantro.
Heat oil in a large wok or skillet over medium-high heat. Stir in beans, garlic, brown sugar, chile pepper, peppercorns and cilantro. Stir fry for 45 seconds. Pour in the water and cover to steam until tender crisp, about 1-2 minutes for smaller beans and 7-9 minutes for the bigger beans depending on the size of the vegetables. Serve immediately.