Bring a nonreactive saucepan of salted water to a boil. Add the beans and cook over moderate heat until crisp-tender, about 5 minutes; drain.
Melt the butter in the saucepan. Add the beans and dill and sauté over moderately high heat until lightly browned, about 3 minutes. Sprinkle with the lemon juice, season with salt and pepper and serve.