Place a steamer basket in a saucepan; add water until it almost touches the bottom of the basket. Bring water to boiling. Add fresh beans. Cover and steam for 18 to 22 minutes or until crisp-tender; drain. (Or cook frozen beans according to package directions and drain.)
Meanwhile, cook bacon in a large skillet until crisp. Drain the bacon; reserving drippings in skillet. Crumble bacon; set aside.
Cook onion in reserved drippings over medium heat until tender. Stir in lemon juice. Add green beans and toss to coat. Heat through. Add crumbled blue cheese or Gorgonzola cheese and crumbled bacon. Heat and stir 1 minute more or until cheese begins to melt. Sprinkle with walnuts. Transfer to a serving bowl. Makes 4 to 6 servings.