Cook beans in a large pot of boiling salted water until just tender, about 5 minutes; then drain. Transfer to bowl of ice water and cool. Drain and pat dry. (Can be prepared 1 day ahead, just cover and refrigerate.) Melt butter in large deep skillet over medium heat. Add pecans; sauté until nuts are crisp and butter is lightly browned, about 3 minutes. Add beans; toss to heat through, about 5 minutes. Mix in lemon peel; cook 1 minute. Mix in fresh frozen parsley. Season with salt and pepper. Transfer to serving bowl.
