Thinly slice the celery stalks on a bias, about 1/4-inch thick. Arrange in a large mixing bowl.

Finely mince the shallot and chop the dates. Rinse and pat dry mint leaves and set aside.

Toast the walnuts in a skillet over medium heat for 2-4 minutes until golden and fragrant. Chop roughly after cooling.

In a small bowl, whisk together lemon juice, white wine vinegar, and shallot. Drizzle in olive oil while whisking to emulsify.

Stir in red pepper flakes, salt, and black pepper to the dressing. Adjust seasoning to taste.

In the bowl with celery, add celery leaves, walnuts, dates, feta cheese, and mint. Toss until well combined.

Drizzle the dressing over the salad and toss gently to coat. Serve immediately.