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 for about 2 minutes. Serve immediately.