Bring a large pot of water to a boil. Place the green beans in the pot, and cook briefly, removing after 3 to 4 minutes. Drain, and rinse with cold water.
Heat the oil in a skillet over medium heat. Stir in the mustard seed and garlic, and cook until golden brown. Mix in the chile pepper. Place the green beans in the skillet, and season with salt and sugar. Cook and stir 8 minutes, or until tender. Season with pepper to serve.