Trim the fennel bulb and slice it thinly. Chop the celery into bite-sized pieces and place them in a large mixing bowl.

Toast the walnuts in a dry skillet over medium heat for 5-7 minutes, stirring frequently until golden brown.

Whisk together olive oil, lemon juice, salt, and pepper in a small bowl for the dressing.

Drizzle the dressing over the fennel and celery, then toss everything together to coat.

Fold in crumbled blue cheese and toasted walnuts carefully to maintain texture.

Let the salad rest for at least 10 minutes before serving.